I tried install the plugin called **gitignore** so many times, and after click **apply** and **OK**, and restart the Android Studio, the plugin is **not in the list**, and in Android Studio, it notified me again to install the plugin.

How to fix it?

I have the idea.properties created in the user .AndroidStudio2.0 folder, and redirect (set) the *idea.system.path* and *idea.config.path* to other folders. That folder have all access from all users. Is it the cause of all these?

-------------Update---------------  

It turns out that all the options are not saved. When I modified the settings, close and reopen Android Studio will reset all modified settings. I already have a solution, allow me to answer my own question.