"Jammed" window on second screen

I use Windows 10, latest version. Problem is with ACDSee, not with any other app.

I opened ACDSee on my main screen, full size. I then opened Help and dragged it over to second screen so that I could have both the Help and the app visible at the same time. When I did this yesterday, no problem; both open full screen on their respective screens.

Today however, the Help screen opened on the second screen, but opened at reduced size and hard up to top right of screen. The problem is that it is so hard up to the top that the tool bar is not visible. I can't alter the size of the display (other than by dragging margins), not close it (no X visible) and worse of all, as I can't see the bar, I can't drag the screen anywhere. All it needs is to be dragged down a bit then I could see toolbar and controls. The only way I can close it is by closing the main app on the first screen.

Suggestions would be welcome.

That works - thanks. It still doesn't display properly until I "Restore" but at least I can now control it. An ADCSee problem.

BTW it's a good program otherwise but a very steep learning curve.

ACDSee is an alternative to Adobe Lightroom. Basically an image management tool with powerful non-destructive editing, like Lightroom.
At present I get a reduced rate from Adobe for their suite of software because I only use it for local community and church charity work - Indesign for village magazine and Photoshop for local event posters and image management. I used to use Dreamweaver for village web sites but as I have moved these to Wordpress I don't need that any more.
Adobe is getting too expensive, even at the charity rate I get, so I am gradually looking for cheaper alternatives, ACDSee is not cheap but it is not a subscription.