I got it to work!
NOTE: The option within Surface Audio is still greyed out and on much like @MicRiley's pictures and posts (thank you for those!).
However, I reinstalled Office and I am now a subscriber to the Office Insider program. This then did some updates and now, following the article in my previous post (and below), I had the options to "Surface Earbud Settings" which allows me to use gestures!
I think that the Surface Audio app needs a patch or fix this or for the PowerPoint update to be pushed out unless it has and my download was just an anomaly!
As a personal tip: If you have videos embedded within PowerPoint, make sure the speaker settings are the ones you want and not the Surface Earbuds! It wouldn't be great in a presentation if you were the only one listening to the content ;)
I hope this solution works for others :)