I am trying to add some snippets using Tools - Global Options - Code - Edit Snippets but I can't see what is written in the lines of the screen that shows up.
I've tried installing Rstudio again, but didn't work.
I'm using Windows 10 and Rstudio 1.4.1106
Have you tried changing to software rendering?, you can change it by holding the Ctrl key while opening RStudio, then you should see this menu and change the "Rendering Engine" to "Software".