When you left click the blue avast! icon a window will open that says Resident Protection with a slider below it. If the window looks different, click the button at the bottom that says Less Detail and the window will change. Make sure the slider is set to Normal. This will change all your modules to Normal. Then click the Details button and look at the individual modules, they should all be normal. You should then be able to change them independently if you want to. If you set any of them to High you may notice that the main slider moves to the middle, this is normal. After you do this, if the individual modules keep changing to High on their own there's a larger problem.
I think the only way it will change to Custom is if you change something in the Customize options, then it should change to Custom automatically.