Why can’t I use it after changing the file to caf format when I create text message ringtones on iTunes?

Open "itunes", select "File" - "Add files to library" in the menu bar

Select the song to be the ringtone and click "Open"

The song will appear in "Music" in "Library"

Right-click the song and select "Show Introduction"

Select "Options" and fill in the "Start Time" " and "Stop time" (within 40 seconds), - "OK"

Right-click the song again and select "Create ACC version"

The same file name appears, but the duration is within Files within 40 seconds

Right-click the newly created song, select "Show in Windows Explorer", change the "m4a" format to "m4r", and select "Yes" in the pop-up window. You can

Then open "iphone" in "Devices"

Select "Ringtones", check the "Sync Ringtones" item, select "All Ringtones", or "Selected Ringtones" , and then select "Sync".

After successfully synchronizing the "Ringtone", the ringtone will appear in the phone's "Settings" - "Sounds" - "Ringtones" - "Customize"

< p>To use this ringtone, just select it. The "Custom" option is above the "Standard" option