If you have connected your device with any other computer, for once only, just for the purpose of charging. You can cancel the syncing process manually from your iTunes by clicking the ‘Cancel’ button.
If you often require you apple device with any other PC to charge it and you don’t want to click the cancel button manually. You can activate the temporary stop syncing option by using the keywords
‘Command + Option’ keys for Mac or ‘Ctrl + Alt’ keys for PC. Remember, you have to press these keys immediately after connecting your device with the computer.
You can also make permanent changes to the iTunes settings so that it may not sync your device when you connect it with the PC. Just open your iTunes and go to ‘Edit’ menu option. Select your preferences. Now, select the Devices tab after which you will see some options on your screen. You have to check the ‘Prevent iPods, iPhones, and iPads from syncing automatically’ box. Then, click ‘OK’ to save your settings.
Now, you will have to sync your files manually to your device for which you have to choose your device from the left column. Then, go to Options and check ‘Manually manage songs and playlists’ box.
To sync your songs or playlists manually, you will have to drag and drop the files from iTunes Library to your device. If you intend to copy multiple files from your PC, you can select them by pressing Ctrl for PC or Command for Mac.