The menu item 'Options->Shortkeys...' opens the shortkeys configuration window:

Click on the box of a toolbox to see the list of all the available commands, and their associated shortkeys.
Click on one of the shortkey to highlight it.
Press 'F1' to get the list of free shortkeys for this command
or toolbox. Press 'Backspace' to remove the shortkey. Press a key to set the shortkey for the command.
A shortkey can't be attributed to more than one command available at the same time.
That's means that the view shortkeys can't be attributed to other commands.
That's also means that a toolbox shortkey can't be attributed to a command.
But the same shortkey can be attributed to two different commands in two distinct toolboxes.
ppModeler also includes shared shortkeys. They are shortkeys available in more than one toolbox.
For example, 'Select', 'Rectange Select', 'Lasso', 'Move', 'Rotate' and 'Scale' are shared shortkeys,
and they must be unique in all the toolboxes they are available.