In case macros cannot be permanently enabled - as explained in this article, - you can set the 'Trust Center' settings back to the more restricted macro setting.
The plugin is digitally signed with a certificate granted by Comodo (an industry accepted security leader) and verified annually before extending the validity.
Macros that are digitally signed by a trusted publisher can run if you have trusted the publisher at the time of installation. All unsigned macros will still be disabled then.
In PowerPoint, go to 'File' > 'Options':
Click on 'Trust Center' > 'Trust Center Settings'
Within the 'Trust Center', open the 'Macro Settings' menu and choose 'Disable all macros except digitally signed macros':