Why do mobile phones often send inexplicable text messages themselves?

There are two possible scenarios for this.

1. Malware is installed. After the common data can be backed up, restore the factory settings.

2. If the screen saver is not turned on, it is best to have a posture password, so that when you walk, you won't accidentally encounter the wrong operation of your mobile phone, and you may send a scribbled short message yourself.