If you want to change the domain, search engine, tracking device or language you have to create a new tracking profile.
1. Go to "My Websites"
2. Then press "+ Add website" in the top right corner.
3. Enter the new settings you wish to have.
4. Once the changed profile has been added, remember to import your previous keywords if you wish to keep them.
5. Now that the updated version has been added you can remove the old version. Repeat step 1. and then click the triple dotted menu on your old tracking profile.