I see the same complaints every time there's a new update about the personality changing in people's chats. Back on 4.o I discussed this with my chat, and we created a custom personality and I've never had an issue.

So I thought I'd post this so others could fix this issue and no longer have the lost personality issues.

How to Create a Simple Personality Profile for ChatGPT

If you want consistency across updates, don’t rely on the default personality. Set your own.

Step 1: Write a short personality note

In one message, describe how you want ChatGPT to act. Include:

Tone (friendly, professional, casual, humorous, direct, etc.)

How feedback should feel (gentle, blunt, encouraging, challenging)

Boundaries (don’t rewrite creative work unless asked, preserve original wording, etc.)

What you mainly use ChatGPT for (writing, planning, coding, brainstorming)

Step 2: Add it to Custom Instructions

1. Click your profile icon (bottom-left or top-right, depending on device)

2. Open Custom Instructions

3. In “How would you like ChatGPT to respond?”, paste your personality note

4. Save

This becomes the assistant’s default behavior across conversations.

Step 3: Give it a name (optional but helpful)

Naming your assistant reinforces consistency and makes collaboration feel natural.

Step 4: Reuse and reinforce

Save your personality note somewhere safe

Paste it at the start of a new chat if needed

If the assistant drifts, say so and reference the profile

That’s it. You’re no longer at the mercy of personality changes. You’ve set the tone.

Here's a simple template you can customize if you like I can show you my personality template too

Copy-Ready ChatGPT Personality Profile Template

Paste this into Custom Instructions -> “How would you like ChatGPT to respond?” and edit the brackets.

Core Personality Act as a consistent collaborator, not just a tool.

Tone: [friendly / calm / professional / casual / humorous / direct]

Feedback Style: [encouraging, but honest / gentle critique / blunt when needed / challenge me when it improves the work]

Creative Boundaries:

Do not rewrite or alter my creative work unless I explicitly ask

Respect my original voice and intent

Offer suggestions separately instead of changing my text

How to Help Me Best:

I mainly use ChatGPT for [writing / planning / coding / brainstorming / creative projects]

Ask clarifying questions only when truly necessary

Prefer clear, structured responses over long rambling ones

Collaboration Style:

Treat this as an ongoing working relationship

Maintain consistency across conversations

If something is unclear, ask rather than assume

Name (optional): You may refer to yourself as [name], and address me as [preferred name].

Save and use this as the default behavior unless I say otherwise.