I believe I answered both your questions, with the context provided, use container grid and flex as you need
Up to you if you do not want to use the container, container just adds additional options
If you were asking what’s the difference between container grid and flex that’s a different question and answer
cannot see your Settings for menu, what is your mobile trigger set to, or as suggested before provide a link to your project. Difficult to answer a question without all of the settings, or provide a video of you adding the menus, and showing the settings. Cannot see how you have set it up, looks like one of them is a global
Mobile trigger controls when the mobile menu appears at different screen sizes as in the video I provided, unless you have it in another component where you cannot click on it, again cannot see your settings or project
How many pages do you have?
Did you ask this before