How to set the format of iphone SMS?

Open itunes. 1. Select File in the menu bar-Add File to Library 2. Select the song you want to play, and then click Open 3. This song will appear in the music library. Right-click the song. Select "Show Introduction" (make sure to click the album option of the song option, otherwise acc creation will not happen) 4. Select "Options" and fill in "Start Time" and "Stop Time" (within 40 seconds) —— "OK" 5. Right-click the song and select "Create ACC Version" 6. Files with the same file name but less than 40 seconds will appear 7. Right click the newly created file. Select "Show in windows Explorer", change the format of "m4a" to "m4r", and select "Yes" in the pop-up window (you must check "Don't hide file type" in the file setting option, otherwise you cannot change the file type name). 8. Check: Find "Preferences" in "Edit" in "itunes" menu bar and open it in "Home"-"Source". Then "OK" 9. You can see the "ringtone" in the "database". Turn on "ringtone" to see if your file has been converted to ringtone 10. Then open iphone in Devices and select Ringtones, check Sync Ringtones and select All Ringtones or Selected Ringtones.