It's very small, to the left, and takes up less than half the size of the page.
You mean the forum appeared wider than half the screen to begin with? The forum content has always been crammed into the left half of the page for me (if it was back then for you too but somehow much worse now, maybe a screenshot would help here)
What browser are you using? Microsoft Edge (the IE replacement)? If so, what about using Chrome?
Also, how about using Zoom? If you have a Mouse with a wheel, then hold down the Ctrl key and scroll the wheel forward (up)
I use Firefox. The width of the Atlas page used to take up about 2/3 of my computer screen, and there was a wider pane for writing comments than there is now, and all the format tabs were normal size so I could see them.
The zoom feature doesn't help with the size of the window pane, just with the font size.
I've never taken a screen shot so I've been tweaking around with that. I have the screen shot but don't know how to post it.
Do you have "Zoom text only" checked under "Zoom" in the "View" menu?