but when i restart Garage Band it's not asking where to find the loops in the new location: what can I do?
Have you restarted the System? In Mavericks restarting an application will not necessarily terminate all processes. They may be cached, ready to resume. If that does not make GB 10 prompt for the loops, move the loops back. GarageBand 10 expects the loops to be in either
- /Library/Audio/Apple Loops/Apple/
- or in your User Library ~/Library/Audio/Apple Loops/Apple/