ChatGPT settings guide

Fill in Custom Instructions (Settings → Personalization) with who you are and how you want answers. It applies to every chat, so you stop repeating it.

Use the fast default model for everyday writing and questions, and switch to a Thinking model only for multi-step reasoning, analysis or code that must be right.

Keep related work in a Project so files and instructions stay together across chats.

Turn Memory on if you want ChatGPT to remember preferences across chats; review and delete saved memories in Settings from time to time.

For long code or document work, start a fresh chat per task. Very long threads carry old context that can lead the model astray.

Ask for the length and format you need ("under 120 words", "a table"). It is the simplest way to cut filler.

Use canvas for editing long documents or code in place instead of asking for the whole text to be rewritten each time.