Are you restarting Opus (e.g. File > Exit Directory Opus, or rebooting)? Or are you just closing the window(s) and opening new ones later?
If it's the latter, Opus continues to run in the background by default, and there are separate configuration options for what happens when you launch the program (usually used to control what happens after a reboot) and when you open a new window with the program already running.
When starting in up in the morning I only have to start my PC, go get a cup of coffee and when I'm back all my apps are started and all windows are in the right place and stay there for the rest of the day.
With Windows 10, Microsoft made a decision to not restore windows how a user positioned them after closing them. Regardless of what changes you make to disable auto windows positioning, windows will never be restored how you position them. This was one of my many frustrating features introduced with Windows 10.
ZMover basically brings back what was available in versions of Windows before Windows 8.
Actually, I'm trying to think of a Microsoft application that doesn't save their position when I exit. I can't. For one work-related website, I have to use Internet Explorer and it opens where I positioned it last. Same with Outlook (in non-maximized view), Excel, Word, Power BI.
Choose Always in the same position if you want it to be where you saved it, and use Settings > Set as Default Lister in the lister itself to save that as your preferred position.
If you're opening a Layout rather than the default lister, then there's a setting in each layout which controls where it opens (you can set this when saving a new layout, as well as when editing existing layouts in Preferences):
If Open layout relative to the monitor the mouse is currently on is turned off, then the layout will open the windows exactly where they were when you saved them.
(In both cases, this assumes the monitors and screen positions still exist. If you save a layout with a window on a second monitor which is then unplugged, the window will be moved to another monitor when you open it, since it would be invisible otherwise.)
(This is also assuming that ZMover or a similar tool is not moving other application's windows after they open. If you're seeing everything not remember positions where things used to, I'd suspect something like that was involved, rather than an OS change.)
Position the Window so that it is not maximized but at the far right edge of your screen touching the edges just like so:
What you're seeing is because in Windows 10 the resizing border around windows is transparent. If you remember back to Windows 7, there was a thick border around windows that you could grab to resize them. That border is still there, but it's not visible.
It's still technically part of the window, and most software has no idea it's there and doesn't compensate for it. (It's also a pain to work out accurately how big it is, especially before a window has been displayed, and if you support multiple DPIs. Microsoft could have done better here.)
Technically, what IE's doing isn't wrong, but it is not ideal in terms of aesthetics, since it leaves what appears to be a gap at the edges of the screen. (The top edge of the window isn't affected because it doesn't have a transparent border, as the resizing border is inside the visible titlebar not outside it. The whole design is a kludge by Microsoft on top of the way Windows used to look/work to get what looks like very thin borders while still allowing you to grab the sides of windows to resize them.)
It's something we do compensate for in Opus, however. So if you want Opus to remember window positions right at the edge of the screen, it will. (12.17.1 beta added a slight fix for the left edge of the screen, for what it's worth.)
Windows that go off-screen will be moved so they are on-screen, but anything up to the visible edge of the window will be preserved correctly, without the need for third party software to move things around.
I was already aware of the transparent "border" that's often used around many windows. If I push the window to the right or left edge and then close it, it does move toward the center when I reopen it. However, after that first drift occurs, it no longer moves no matter how many times I open and close the window.
So, it is remembering the window position, but it's also obeying a rule of opening the window completely inside the screen area. Since the transparent border is part of the window, Windows the application has to move the window over enough to fit inside as well.
Since the transparent border is part of the window, Windows has to move the window over enough to fit inside as well.
It's not Windows that moves it. Windows will let you open a window completely off-screen if that's what you ask for. It's the applications that (sometimes) move their windows to ensure they're completely on-screen.
Which is usually a good thing. The transparent border complicates things a bit, and not much software has been updated to account for it, but Opus has and does.