Up2Vex this is not something that we can change. It is related to Flarum or an extension. You will have to report it to the developers. It might be enough to apply some CSS fix, but I don't know what CSS code to use, sorry. What you can do is try and look into your browser's dev-tools for possible errors in console or CSS styles. If you tell me your forum name, I could look into this for you instead, when I have some spare time.
The permission issue is likely related to incorrectly set permissions in the admin dashboard (or an error in an extension)
TB54 sorry, I know what you mean now. Currently, there is no way for forum admins to put their forums in maintenance mode at FreeFlarum, AFAIK