Even writing this small post, my cursor has jumped back three times
So it is not Writer causing the problem!
It sounds like "tap to click" is enabled on the touchpad which means that every time you touch (even brush against it if set to extremely sensitive) the touchpad you are likely to send a left
mouse click which causes havoc. Test by putting the
mouse arrow on a line of text and then tapping the touchpad once. Does the cursor jump to where the
mouse arrow is?
On some laptops - my Acer for example - you cannot even disable it! You should be able to disable "tap to click" by right-click Start (or Settings) > Control Panel >
Mouse > Touchpad settings - it is the right-most tab. If you decide to keep it, and I strongly recommend that you do not, then set the sensitivity to as low as possible. Setting it so you need to stamp on the touchpad before it sends a click is about right.
There is no 'undo' facility.
As they say in the pantomimes, "Oh yes there is!". ctrl/z undoes in any application including Writer. So does Edit > Undo ..., and clicking the anti-clockwise arrow icon. Writer allows you to undo about 100 steps - change it by Tools > Options > OpenOffice > Memory > Undo ...
If this solves the problem, please click the Edit button on your
original post and add [Solved] in front of your subject.