Click on "Hot keys management" button. This will bring up hot keys management dialog:
Each tab on dialog represents its own menu:
|•||Main menu - appears after right click on program icon in system notification area.|
|•||Note - appears after right click on note (excluding edit area).|
|•||Edit area - appears after right click on note's edit area.|
|•||Groups - represents Show/Hide options for groups.|
Enter desired hot key (e.g. Ctrl+Shift+H, F10, Shift+F9 etc) in the text box (do not type "Ctrl" or any other text, just press on desired keys combination) and press OK. Take into account that there is a number of forbidden combinations listed here.
Clicking on "Defined hot keys" will expand the list with hot keys you've already defined:
Hot keys previously saved will have icon next to them, while just added hot keys will not.