Hi @eddiejbaker,
I'm afraid this isn't customizable. And to be honest that's one of the reasons why I only sync my runs to Strava once the activity is done (as opposed to directly recording with Strava). The default workout app on my AW allows some pretty decent options to customize the screen - and also allows scrolling between more screens if needed. So by default, I use a screen with actual, rolling (1 km) and average pace. Or I scroll to another view with actual & average pace, and HR. Or yet quite different views with running power, HR zones, … and yet a different view for intervals (to see specific time & pace for the current interval). Tons of options that I don't really expect Strava to ever implement, but well, I’m personally happy with my setup, so I don't mind.
If you'd like to suggest the Strava app behaviour change, you might want to check the Ideas section of this hub to see if this already was proposed (and you can add your vote), or submit a new idea.
Thanks for your reply Jana - just seems a shame to switch to a different app etc. when it did display average pace (and I was perfectly happy with the setup) up until a few weeks ago! Surely a toggle would be an easy change to implement.. I will give the ideas a go, thanks.