Just be sure you install the NEW FS9 Addon Manager, which is the only Addon Manager we have online, AFTER ALL SCENERIES.
If you reinstall any scenery, you must reinstall the updated FS9, because the sceneries installers hasn't been updated with the latest Addon Manager, so installing a scenery after the updated Addon Manager will downgrade it to the previous version, that's why the latest Stand-alone Addon Manager MUST be the last thing you install.
I already replied to you about this, several times, there's no other way, and this works.
Just be sure you DO NOT set any "Compatibility" mode for the FS9.EXE. There's no need to set any to run in Windows 10, it works by default so, but if you did that, it might interfere with the activation.