GPS speed readings

Power up the Virb, press MODE and choose SETUP, choose SYSTEM, choose UNITS and choose STATUTE, then OK.

He's not asking about the VIRB, but about VIRB Edit. The VIRB records in metric. But the idea is the same. Start up VIRB Edit, choose VIRB Edit->Preferences, set as desired. Then "Create Video", drag what clips you'd like into the video, click on "Overlays" at the bottom of the window, and choose one.

My apologies for reading his question wrongly, thanks SCHINDER for pointing that out.

What are you trying to do? The operation you're using is intended to replace/add a GPS track to your video, so it's asking you which one. Navigate to the track and add it.

Faded font implies that it's not in a format VIRB Edit can read. What format is the track in?

You're talking about a VIRB Elite, and not a regular VIRB, right? VIRB Edit doesn't do that on my Mac Pro, so I suspect that there's something unique about your desktop machine that's screwing things up. VIRB Edit should automatically find (and does for me) the appropriate GPX files on the VIRB Elite. You should only need to edit the track if you want to replace it with the track from another device.