I was going to suggest the highlighter add-on but it appears to have become abandonware.

I hadn't realized, but another add-on I do already use has a highlighting option too. This I learned from the user comments on the highlighter add-on's webpage. So try the Extra Format Buttons add-on:

https://codefisher.org/projects/extra_format_buttons/

You may have to customise the formatting toolbar in your Write window to make this highlighting option visible.

Thanx for ur prompt response. I am a novice on the pc re installing things etc. Went on to the site you suggested but very unsure as to how I download that site and to where and how to customise the formatting toolbar. Sorry to be a nuisance but any detailed step by step guide would really be appreciated. scotjeph

Zenos said

I was going to suggest the highlighter add-on but it appears to have become abandonware. I hadn't realized, but another add-on I do already use has a highlighting option too. This I learned from the user comments on the highlighter add-on's webpage. So try the Extra Format Buttons add-on: https://codefisher.org/projects/extra_format_buttons/ You may have to customise the formatting toolbar in your Write window to make this highlighting option visible.

The Extra Format Buttons add-on partly works here in TB 52.3: the sub/superscript and strikethrough buttons appear on the Formatting Toolbar, along with the pixel selector, but the extra buttons including highlighting aren't available via View/Toolbars/Customize... This is probably because the add-on is labelled 'not compatible with 52.3'. Without already having the Disable Add-on Compatibility Checks add-on installed, EFB won't install and provide even the basic buttons. It might install fully in an older TB, then continue to work as TB is updated.

On the other hand, Highlighter installs and works in 52.3 for the most part.

How to install add-ons.