How to rename annotation pen name? (Note.001 -> something else)

It says “double-click to rename”, but nothing happens. Double-click where? On the name? On the colour rectangle? None of them worked.

It is Ctrl+LMB Just forget about that tooltip :wink:

Then why does it say “double-click”; is that a bug?

Its a wrong text in a tooltip. I would not call that a bug. That thing is a customization of a predefined listbox element in blender and if I remind correct its simply the default message that comes with it.