How do I reset a default app for music

[zmsc1]

I have a OnePlus 3T, updated to Nougat and have installed Poweramp, which I want to use as the default music player. I've gone into settings, apps, poweramp and clicked open by default. That shows "No defaults set" and Open supported links (which I think is meant to set it as the default) is greyed. So clicking a music file in file manager has no effect. If I go into Poweramp and navigate to a music file, it plays.

 

[N4Newbie]

Go to whichever app is the current default (Settings -> Apps _>...) and clear the defaults for it first.

 

[zmsc1]

Thanks for that advice,

My first guess about how to set the default was to go to the settings of the app I wanted to set as default, which I did, and set Poweramp as default. That had no effect, so I did some reading and found out that I needed first to go to the settings of the app I thought I'd replaced as default. Sorry, I know that's complicated, but Google Play Music had been the default, so that's the one I went to and I cleared defaults, as per your advice (except that I'd done it in the wrong order).

That also had no effect, so I disabled Google Play Music then wend back to the Poweramp settings - but now the settinges are greyed, so I can't set a default at all. Is this just Googles way of telling me that they make more money if I use their apps?