Build command at the top

Hello, I am close to releasing my first game:) I have about 50 levels. Hovering over the Build button at the top it looks like this builds everything on the level your on and every other level you have in your project.
Is this true or do I need to open every level and build each one individually before I get ready to ship my game?
When I am ready to build everything what type of build should I use. Initially, I was going to create a Standalone game. Where do I turn on maximum build to render everything out for delivery at the best quality?
After I am done building everything I am not sure if I should choose under Automation in Unreal Engine 4 Build and Submit or what? In the past I have pressed the Build and submit but I am not sure what that does.
A bunch of code left and right that just keeps coming. Should I just wait for several hours while this does it’s thing?

Thanks for any help:-)

As far as I know Build,builds every level.It can take 10 mins to days,depends on your levels.Especiall lightining complexity.Build and Submit is for building stuff and sending them to a source control.Think like sharing your project with fellow devs in same company.But seems like you’re on your own so there is no need for it.The thing you must do is “packaging” to distribute your game.Packaging,creates the end product for user.