How to delete SMS automatically?

SMS messages are automatically deleted for several reasons:

1. Check whether "Delete old information" setting, information, more, settings, more settings, delete old information and close are on or off;

2. If it has been turned off, check whether the third-party SMS software is installed in the mobile phone to see if there are relevant settings;

3. If the mobile phone still deletes the SMS automatically, back up the data in the mobile phone and try to restore the machine to the factory settings.