For Mac computers please download Android File Transfer to your computer.
For PC please follow the instructions here.
On Ski Tracks, go to Tools > Track Backup > Backup.
This will create SKIZ files of all your tracks in the directory Ski Tracks/Backup on your phone.
Move the entire Backup folder from your phone to your computer. This will ensure you have a full backup of all your tracks if you lose your phone or the phone is reset. Also, by moving the Backup folder you will reduce storage requirements of Ski Tracks.