Settings
What would it be for an add-on without any options to customize its features. Pontoon Add-on settings are accessible from the toolbar button context menu as mentioned above, or from the browser add-on or extensions management.
In the settings page, you'll find options to select your locale team (if not identified automatically), adjust notifications update interval or change the toolbar button behaviour.
From the advanced options, you can also specify the correct container, if you use this feature in Firefox to access Pontoon.