The master page of a module is the page where it was initially added and configured. When sharing a module across all DNN pages, it's only possible to modify it from the master page itself. When attempting to edit the module via any page other than the master page, the following error is shown:
It may be necessary, however, to change which page is considered the module master page. There's no direct way via the UI (this has been brought to the developers as a feature request) but users can achieve the same effect with the following workaround.
Requirement: Admin access to the DNN portal
1. Log in to the DNN portal with your admin credentials.
2. Go to Content > Pages.
3. From the left-hand page tree, click on the current master page and then the Delete button to move it to the recycle bin.
4. Click on the name of the target master page from the left-hand page tree and then the three-dot icon to select Edit.
5. When the page opens up in edit mode, you will see the following message on the module:
6. Click the hyperlink to Make this page as master.
7. Once completed, validate that you are now able to use the admin cog to edit the module.
8. Go to Content > Recycle Bin and select the previous master page then hit the restore button.