I boot to a Winows or Mac screen. This is set by options in the operating system (for Windows, right click on the screen).
When I open a browser, Chrome goes to a Google blank, Firefox to a Firefox blank, Safari to a Safari blank. each browser has its own way of setting this "home" or default page. I used to go to Yahoo, but they moved to formats I didn't like, so now I'm starting with home page blanks.
To get to this place, I have a bookmark in each browser to the rv.net portal. On most of my browsers I've "remembered" the ID and password, but make myself enter a password each time on portable or pocket devices. For whichever portal you are using, you can get to the home page at the top of any page you are on, and bookmark that. If this is all you do online, you can make it (or the forums page) yor browser's home page. Sounds like you've accidentally made a particular dialogue your browser's home page, but unlikely that your computer boots to it as a background screen.
Tom Test
Itasca Spirit 29B