Streamline editing system instruction and model options for each chat

I know that it's possible to edit the system instruction and the model parameter, but I either have to create an agent for that or start the first prompt and then be able to edit the model settings for the current chat only. Otherwise, the settings will be aplied to all future chats. I almost never want to do that.

When I want to change the temperature for example, it's almost always for 1 chat only to experiment! Perhaps add BOTH the option to change settings for all chat or for current chat only

Please take a look at how MSTY implements it. It's pretty much perfect!