You almost had it. Go back to Options, you were right to go there. Click on the Editor icon, and look below the mock editor. You should see an option for “Use block insertion point”. If you check that off you can then use the width field beside it. The default of 6 pixels looks a bit like an old school cursor, but it doesn’t work as well with variable width fonts. Setting it to 2 or 3 works better with them.