Move your save files
To backup your profile you need to grap folder with the game files and zip it.
Folder is located at: C:/Users/YourName/Documents/AmericanTruckSimulator/profiles
There you will see folders named like: 4E696E75C5A16B61 etc.
You just need to .zip or .rar folder with your profile and move it to your another computer. If you have more profiles just pack whole folder /profiles
You can use OneDrive (if you have windows 8 and newer) for sharing this folder across your computers.
Have fun !