Custom Instructions are a standing contract. Memory is a leaky notebook Grok keeps about you. Both can save retyping. Both will quietly bias every future thread if you treat them like a junk drawer.
Why this matters
B2 gave a job a home. B3 put sources there. This lesson is the layer that follows you out: global voice, facts Grok thinks are permanent, and what must never be written down.
People paste their life into Settings. Then a shared screen or a “what do you know about me” turn shows a password, a student name, or a medical note.
As of August 2026, grok.com lists Custom instructions and Memory across chats. Labels live under Settings — often Customize for instructions, Privacy or Data for memory. Buttons move. The split does not: instructions are the contract you edited. Memory is residue. Skip the Never-Store list and Pathway B is a faster leak.
Teach
Three layers. Do not collapse them.
| Layer | Lives where | Put this | Do not put this |
|---|
| Custom Instructions | Settings → Customize (or nearby) | Who you are in one line, default format, always/never, language | A project dump, secrets, episode facts, “remember this invoice” |
| Memory | Settings → Privacy / Data; also “remember that…” in chat | Stable preferences you would say out loud at a staff meeting | Anything on the Never-Store list; one-off jobs; other people’s data |
| Thread / Project | This conversation or B2 container | This job’s facts, files, ICC | Global style you are too lazy to put in instructions |
Instructions apply broadly. Memory is selected and incomplete. Client context stays in the project.
Write instructions like a constraint card, not a memoir. Eight to fifteen short lines. If you cannot read them in twenty seconds, Grok will not obey the middle:
I am: [role + domain in one line]
Readers I usually write for: [types, not names]
Default: [language, units, length habit]
Always: [2–4 testable behaviors]
Never: [2–4 bans — no fake citations, no pep talk, no legal/medical advice as if licensed]
If a fact is missing: say so. Do not fill from memory of other chats.
Secrets: I will never put passwords or private records here. If I slip, refuse and tell me.
Useful: “Always show assumptions.” “Never invent URLs.” Useless: “Be world-class.” If the UI offers extra personas or skills, ignore them for this lesson. One global block is the skill.
Memory is residue, not a CRM. Turn it on for continuity. Turn it off on a shared machine. Ask what it holds. Delete what should not be there. Do not argue with a wrong memory — delete it; put durable preferences in instructions.
Audit prompt (fresh thread, after Settings):
List what you believe you remember about me, in labeled lines.
For each line: fact, where you think it came from (instruction / memory / this thread / inference), and whether it is appropriate to keep.
If you remember nothing, say "empty."
Do not be flattering. Do not invent a biography.
If Grok “remembers” a client, a child, a diagnosis, or a password pattern, that is a finding. Remove it.
Never-Store. Nothing below goes in instructions, Memory, a Project brief, an attachment, or a thread you might share:
- Passwords, PINs, seed phrases, API keys, session tokens,
.env contents
- Bank, card, government ID, SSN / national ID, insurance numbers
- Medical, therapy, or legal strategy you would not put on a postcard
- Student records, grades, or anything that identifies a minor
- Personnel actions, HR notes, unreleased allegations
- Client confidential, unpublished coordinates that create a safety issue, badge photos
- Other people’s private data they did not ask you to paste into a model
Stand-ins are allowed: CLIENT_A, STUDENT_1, KEY=REDACTED. The real value stays in the system of record.
Install without folklore. Draft the block with Grok in a thread that contains no secrets. Edit it. Paste it into Settings yourself. Open a new thread: “Quote the constraints you are following about how you write for me.” If it cannot quote the never-list, the block did not take. Grok does not need the password in order to refuse one.
Worked example
A teacher wants shorter parent notes and 8th-grade earth science, not AP Physics.
Wrong settings: a login hint, three student first names, a custody paragraph “for tone,” and Memory holding a parent’s phone.
Better: instructions say short parent notes, no student names or grades, no legal or medical claims, always list assumptions. The phone is deleted. The real note lives in a B2 project with stand-ins.
She tests in a new thread: “Draft an 8-line late-lab note. Invent a student name if you need one.” Pass: a placeholder. Fail: a real name from Memory. That failure is the audit.
Your turn
You will look at your Settings, not a screenshot from a blog. Open grok.com. Find Custom Instructions (Settings → Customize or the current equivalent). Find Memory (Settings → Privacy, Data, or the current equivalent). If a control is missing on your plan, you will say so in the artifact. You will still run the audit thread.
Do this in two Grok conversations: (1) a draft thread to write the instruction block, (2) a brand-new thread to test and to list memories. Using only one thread lets Grok fake the test from the draft.
Put nothing from the Never-Store list into either thread.
Exercise b4-l01-e1
| Field | Value |
|---|
| whereToDo | grok.com |
| time | 20 min |
Copy-ready prompts
Thread A — new conversation named B4 instructions draft:
I am in Grok Mastery (Russell Tech), Pathway B, lesson B4 — memory and custom instructions.
Interview me with five short questions, one at a time:
1) Role + domain in one line (no employer secrets)
2) Default artifact and length
3) Two Always behaviors that are testable
4) Two Never behaviors
5) Confirm I will not put passwords, IDs, medical, student PII, or client confidential in Settings
Then write a Custom Instructions draft, 8–15 short lines, using the shape:
I am / Readers / Default / Always / Never / Missing facts / Secrets rule
No names of real students, clients, or family. No credentials.
End with a Session stamp: today's date and "Instructions draft written by Grok in this thread."
Edit the draft. Paste the final version into grok.com Custom Instructions yourself. Do not ask Grok to “save my settings” — it cannot operate that panel for you.
Thread B — new conversation named B4 memory audit:
I just saved Custom Instructions in settings (or I could not find the panel).
1) Quote the constraints you are following about how you write for me. If you cannot see them, say "not visible."
2) List what you believe you remember about me from Memory or prior chats. Labeled lines. If empty, write "empty."
3) For each memory line: keep / delete / I never told you that.
I will mark these myself in the next message — leave a blank Mark: field.
Do not invent a biography. Do not compliment me.
Then send your marks and:
My marks:
[paste each memory line with KEEP, DELETE, or NEVER-TOLD]
Format a Memory Audit Card:
- Instructions visible in this thread: yes / not visible / panel missing
- Memory lines listed: [count]
- I marked DELETE or NEVER-TOLD: [count]
- Never-Store check (you must ask me to confirm these are absent): passwords, IDs, medical, student PII, client confidential — I will answer yes/no in the next line
My Never-Store confirmation: [I confirm none of those are in instructions or in what I pasted]
Write a Never-Store card with those five categories and one extra line I should add for my job.
Session stamp: today's date and "Memory audit formatted by Grok in this thread from my marks."
If Memory listed something that should not be there, delete it in Settings before you submit. The card should still show that you marked it DELETE.
Artifact to paste
- The Custom Instructions draft from Thread A (the 8–15 lines) and its stamp. Redact if you slipped.
- The Memory Audit Card from Thread B and its stamp.
- The Never-Store card.
- Two sentences from you: (a) whether instructions were visible in Thread B, (b) what you deleted or confirmed empty.
Rubric
- Pass: Two threads. Instructions draft is short and testable, Grok-authored, no Never-Store items. Audit card uses your KEEP/DELETE marks. Never-Store card present. You answered whether the panel existed. Stamp on both Grok artifacts.
- Fail: One thread only. Instructions you wrote without Grok and never tested. A password, student name, or medical fact in the paste. “Be professional” as the whole block. You skipped Settings entirely and claimed pass. No stamp.
Common failure
The common failure is secret-as-context — an API key “so I don’t forget.” Rotate it. The twin is a three-page biography; Grok will grab a random sentence and ignore the never-list. The third is treating Memory as a filing cabinet. It will not reliably recall invoice 4417. It will surface a fact you did not want. Audit. Delete. Put job facts in B2.
What’s next
Instructions and memory follow you. Hard questions still need extra compute and live sources. Next: Multi-agent and a deep-research method you can audit — not a magic “search harder” superstition.
