How to save user preferences?

Every time I open up Blender, the user preferences go back to the default. Is there any way to save them? Even when I open a file that I’ve already changed the preferences in and saved, they revert to the default. Thanks for your time.

For the changes/addon enabling/etc you did in the User Preferences, it’s File -> User Preferences and click on Save User Settings from the bottom of the User Prefs panel

For saving your UI modification/in Blender edits etc… as the default it’s File -> Save Starup File.

Now it’s important to know that when loading a blend, if you have “Load UI” enabled (by default it is enabled) , it will load the UI that has been saved with that blend.
So either make sure to disabled Load UI from your File -> Open browser , or disable Load UI in File -> User Preferences -> File (and save user prefs so it is the default behaviour to have Load UI disabled)

From the keyboard it is ctrl+u key