How can I set my curser in Libre to highlight rather than make text invisible

I have asked this question before and checked the Libre site but my question has not appeared. For some reason when I now try to highlight text in Libre by moving my cursor across the text while left clicking on my mouse, the text becomes invisible rather than being highlighted. I am sure it is not a problem with my mouse settings because the cursor highlights text when I use it, for example, to edit an e-mail in my Thunderbird program.

Just a guess, but maybe the Format Painter got stuck on and is set to the same color as the page background.

Thanks Paul but that does not seem to be the solution. I clicked on the Format painter icon but all I ended up doing was removing it from the tool bar. I guess I will have to remove the Libre program and download a new one. Rob G.

Paul: Viola! Yesterday while I was typing in Libre the screen went blank, like with a power outage but I do not think we had a power interruption and when the screen reappeared I clicked yes to “recover the document” and the “lost” text reappeared. Since then the cursor works the way it should-highlighting the text. Only change is that cursor now is a straight line attached to a triangle which changes to a double triangle when I am in the middle of the page. What happened? Thanks RobG