Maybe something like when you have changed a setting, 'Apply' gets 'un-greyed-out'™, and a 'Cancel' button appears?
It's considered bad UI behaviour to have buttons that affect the state of a dialog box appearing and disappearing.
In this case, that should be a button labeled Revert
which is enabled only when a setting has changed. Your other programs in the screenshot have this.
Also see my previous reply about why MusicBee's Preferences dialog being non-modal confuses the matter somewhat with regard to Apply
It may help to know how many people actually use the Apply
button on the Preferences dialog to make adjustments on the fly.
I must spend as much time tinkering in that screen as anyone else, but I never use it that way.
If no one would miss it, making it modal and just having OK
buttons would remove any confusion.
Bee excellent to each other...