Android phone, when sending text messages, becomes MMS. How can I set it to cancel this?

How to turn SMS sent by Android phone into MMS: 1. Check whether the "Subject Bar" is open in the SMS editing interface, and press the menu key to close it; 2. Enter the SMS settings to see if there is an option of "converting SMS to MMS" and close it; 3. Enter the SMS settings to see if there is an option of "Remind when SMS is converted into MMS" and turn it on; Fourth, send long short messages through third-party software (search for short messages in any application market and choose to download, install and use them according to personal needs).