Bottom Tab "Conventional Frequencies".
Highlight the row/s to edit.
Left Click in a highlighted cell in the "Squelch" column.
In the pop-up "ToneSetForm" window make selection/s.
To get the "Conventional Frequencies" tab, you will need to enable it using the "Advanced" drop down menu. Once you have the tab enabled, you will be able to go to it to make the changes you want.