You can check 2 settings for this.

What I always do is give the background menua colour, just for test so you can see what space you need to work on.

Relative settings are:

height of menu in the template

position of menu in the template

margins of the menu in the template.

or in the main menu itself: (where you can set for test a background.

the margins (just play with them and see what it does)

Also you can check the margins of the objects that are close to the menu.

But be carefull, make a copy of the project and work / test with that one.

handle 1 option at the time.

The background trick can also be used for other objects offcource, after you know what does space in what way you and corrected this then set the background colour back to it's original.

Goodluck.