Re: how can i stop auto download unwanted software on my phone?
When you say unwanted software, are you referring to pre-installed applications or are new random software being downloaded?
Going by what you said, I'm gonna assume, you are on a limited data size plan. By default, the Google Play Store is set to keep all apps up to date. This can be changed by opening the Play Store app. Top left hand corner click the 3 vertical lines (menu) and go down to settings. First option under sittings, change to "Do not auto update".
Or
You could set it as "auto update app only over wifi" which will keep your apps periodically updated and not use your mobile data.