Welcome!
It’s a really simple adjustment to hide elements; you need to look at the Display configuration and simply set it to None to hide the element, and whatever else to have it shown.
Top = visible (as flex)
Bottom = Hidden
For different text, you would have two elements and show one for certain breakpoints and hide it for others, swapping it with the other one.
To select and work on hidden elements you’d use the Navigator pane only, and you can see the hidden elements indicated with an eye icon to the right;
Have a play around with these buttons on some elements and breakpoints and it’ll come clear pretty quickly.