Taskbar size

Oh how I hate Windows 8.

Last night I wanted to do something quickly so, instead of using a
proper W7 laptop or an Android tablet, I picked up this Wimboot W8.1
tablet.

First it tried to get me to upgrade to W10, which would be stupid as it
would load an uncompressed OS instead of the present small compressed
one.

Then I must have put a finger in the wrong place, and got a HUGE taskbar
with a small desktop screen. Today I've fiddled round for ages and got
the taskbar to the bottom half of the screen. But I seem to have no way
to get to the two little resize arrows, so it just sits there.
Eventually , by turning the tablet through 90 degrees, I got the taskbar
at the bottom of the portrait shaped screen, which let me reach the
"Apply" button of the Window that reduces the size of the icons.
Rotating back to Landscape then has the taskbar only taking the bottom
third of the screen.

How can I set the desktop screen to the original default settings?

I think then I'll have to restore the machine back to its delivery
status and set it to never update. The last thing I need is a small
machine that works worse than any Android tablet and that wants to
install a wrong OS.
--
Bill