Preferences - Hotkeys
To open your preferences, click the your avatar at the bottom left of the Tuple popover and select Settings from the dropdown:
You can also use the keyboard shortcut cmd + , to bring up the menu.
Then select the Hotkeys tab:
Here you can set custom hotkeys to trigger various actions when using Tuple. Just click "Record Shortcut" and enter the sequence you'd like to use for each action.
You can scroll for ever more options than shown in this image.