A big thanks Lou. Since I predominantly access the forum via PC, I don't always remember to check other views such as phone or tablet.Note the right hand column shown in Tom's screenshot above is not available on a phone display or on some RV Forum pages such as New Posts, Resources, and several others where the primary window expands to the whole screen.
In this case, scroll to the very bottom of the page and just above "Contact Us - Community Rules - Terms and Rules" etc. you'll see a little paint brush with either "RV Forum" or "RV Network Dark" next to it. Click on this and you'll open a Style Chooser dialog box that lets you select the style you want