From the Settings window, pro plan users have the option to insert custom instructions.

These custom instructions allow you to give commands to the AI that carries across ALL conversations regardless of context. For example, if you have specific style requirements for your project, this would be a great place to provide that information to the AI.

Note that custom instructions only apply to new conversations after they are added or changed.

Additionally, note that simply due to LLM limitations, some custom instructions CANNOT be followed, such as using specifically tabs or spaces for code snippets.