How do I get ChatGPT, Claude or Gemini to remember me, my work and how I like answers?

Three settings do different jobs. Custom instructions are standing rules for every chat: who you are, how long answers should be, which language to reply in. In ChatGPT they sit under Settings, Personalization (1,500 characters on Free and Go, 5,000 on paid plans), in Claude under Settings, Your Claude, and Gemini has its own instructions setting. Memory is what the assistant picks up from past chats, and all three let you review it and correct it. Projects keep the chats, files and instructions for one piece of work together, such as a house move or an exam; Claude's free plan allows five. Use a temporary or incognito chat for anything you do not want remembered.