Easy - I don't know much about the P3 or the P3 DJI app, but you can use a 3rd party app with a flight logger (I use Litchi, an Android app, but there are others available), then export to DashWare. From there you can customize the video display overlays of your flight parameters.
There are many threads about DashWare, which is now free. It's a great tool.
As @volito said, use Dashware. And you can export the flight logs from your bird and convert them into a profile that works with Dashware using a couple online tools. I don't have the links handy, but if you search the forum they should be easy to find.