Navigation bar for the elderly

[J0A]

I have bought a Galaxy Tab s10 Ultra for my mother, now that her TV broke. Figured she might as well upgrade to a more versatile unit —and her whole setup was so outdated it was tough to even find such a small television(27" so it could fit in her cabinet and with SCART, because her TV-box only used SCART).

So now she can watch her favourite TV-shows and play sudoku and call her sister and you name it ... what's not to like?

The navigation bar! 

Why oh why does it disappear, when she watches television or use any other full screen app?

She is old = slow with terrible eyesight and do NOT know how to swipe properly.

When she does manage to swipe and have the menu come up, is disappears almost instantly. 

Please let us choose whether to have the navigation bar always display on top of apps or not, and let us be able to make those buttons bigger and more visible (higher contrast and solid forms) and let us decide where to place them (and lock them there).

It took a lot of convincing to have my mother use this device and the way the navigation bar is working out of the box has not been helpful to say the least.