;
, If you can't see it, try hovering over "Ubuntu Software Centre".
, A minus (-) like the default setting for "Source Code" means only part of it is enabled (by the way, source code means "let me download source code for all my "Ubuntu Software" repositories"). To add/remove/edit/enable/disable a different repository, continue to Method 2.
Open the Ubuntu Software Centre.
Click on "Edit".
Click on "Software Sources...".

,
If you want to enable/disable "Ubuntu Software" Repositories, just check/uncheck the tick boxes to the right of each repository entry.
{"src": "wikihow-all_validation", "title": "How to Edit Ubuntu Repositories1"}