One option would be to delete the activity already loaded in Strava and just do an import of the .tcx file directly into Strava (export from Garmin Connect and import to Strava using the “+” - “add file” option).  As far as elevation editing goes, I don’t have any real experience with that.  Seems like you might have to edit each specific GPS point which could be very tedious and error-prone.  One option (assuming it is available) is to use the “correct elevation” option once you load it into Strava.  That often helps correct for errors in device recordings.

Thank you for the reply! Yes I have figured all that part out except for editing the elevation in the text string. I am looking for what specific field or part of the text string to add the elevation overriding what is in there in the export.

There is no such summary in tcx files, Strava calculates the elevation with the provided <AltitudeMeters> in the trackpoints. You can try the “correct elevation” option in STrava to use Stravas elevation maps instead.