How to set multiple ringtones for iphone4s?

1. Import songs into itunes, and then you can play and display them in itunes. 2. Find your favorite song, right-click-show introduction-options-start time and stop time, and modify the time yourself, and the time must be within 40 seconds. -create AAC version. 3. Click the 40-second song generated under the song just now, and right click-display it in WINDOWS Explorer. A pop-up window will appear. You can change the file .m4a in this window to .m4r format. 4. Copy this file to a random place, as long as you can find it, and then add it to the ringtone in itunes. 5. Connect the phone to the computer, drag the ringtone from itunes to your phone, and select ringtone synchronization, so that the ringtone will enter the phone without anything else moving.