I have a FR30 and am replacing it with a FR35. Do I need to back up my data history and unistall the FR30 app and reinstall a new FR 35 app on my phone and pc? If so, can you advise how to do the back up.
No need to uninstall/reinstall/backup anything. Just add your new FR35 to the garmin connect app, and remove your old FR30 once you're done with it.