Change the file extension from .m4a to . Confirm the change when prompted. Sync to iPhone 4s :
Here is a simple guide on how to download and set a ringtone for your iPhone 4s.
Right-click the new AAC file and select (or Finder on Mac).
Follow the in-app instructions, which usually still require a quick sync with iTunes to "activate" the tone. Once the file is synced: Open Settings on your iPhone 4s. Tap on Sounds . Tap on Ringtone .
