Mike,

UPDATE:
After going through a number of threads looking for a similar challenge to mine, I tried the "hold the Shift key while launching Qimage" option which just added to the frustration, having everything reset in my working Qimage window...but that was expected and would have been worth the effort of resetting things back to my personal preferences had it solved my issue.

What solved the problem was to open Qimage, which opened on the middle display, moved and resized it to the left 4K monitor and set the Live View/Thumbs to my liking (as usual) and then opened the Windows Display Settings for my monitors. For my system settings, my middle monitor is selected for "Make this my main display" and I changed that selection to the left 4K monitor where I work with Qimage. I closed Qimage, restarted the computer/laptop and launched Qimage (wait for it...wait for it.....) and it opened on the left 4K monitor with my preferred settings! I then opened the Windows Display Settings for my monitors again and set the middle display (1920x1080) back to  "Make this my main display" again. Restarted the computer and opened Qimage. Now it is like it used to be, always opening on the left 4K monitor, before Qimage started opening on the "Main display" (middle) by default.

For those of us who don't write code and have a vast working knowledge of how everything works and interacts, Windows can create many challenges along the way in using our computers. I don't know if my solution can help cdx54, or put him on a path to find his solution, but I thought I should post the END of my story. Thanks again for your terrific software and support!!

Thank You, Mike!

My bad for overlooking saying my monitors are in the "Extended” mode earlier. You’ve answered my question and the problem is on my end. My three monitors; 1) Dell XPS laptop display on the right at 1920x1080, 2) LG 32” 3840x2160 monitor on the left and 3) HP 24” 1920x1080 in the middle and each monitor has it's own Color Profile. If there’s been no change in Qimage in years related to window position on multiple monitors, the problem is on my end and that’s what I was hoping to figure out so I could pursue the next steps in coming up with a solution. There was another event/activity during the mentioned time-frame that I will investigate now that you’ve confirmed the issue isn’t related to an update.

Thank you so much for your help and for such an awesome Program!!!

Thanks, Mike.

As I stated early in my rambling, everything was normal up until late summer or fall and that's when QiU started defaulting to the main display when opening (main being toolbar, etc. location). I was hoping there was a setting associated with Qimage as to which monitor it opened/appeared on and would retain the window settings for Thumbnails and Live View. It's not a big deal and I've been dealing/living with it for a few months and can continue to do so if there's no magic setting to save and recall. I'm coming up on 2 years of use with Qimage and have it running most of the time. Again, maybe its a Windows thing.

I have an annoying (personal) item that began sometime last summer and I'm suspecting it is associated with an update during that time.

Whenever I open Qimage Ultimate, it defaults to the Main display (middle Display of 3) and changes the last used Thumbnail and Live View settings (size) rather than opening on the last used monitor with the settings I now have to reset each time. I'm sure there is an option for saving your setup for Qimage to open with the last used UI settings, because it always used to open on my large (left) monitor that I'm having to move it to whenever I now open it. I haven't been able to find a way to save and recall the UI settings in the Preferences menu or other Save options. I realize this could be a W10 issue, but...if there's a QiU solution, please let me know. Maybe I shouldn't be referring to this as "User Interface" but that's what comes to mind for a description. I can give more system and QiU details if needed. TIA!

Thank you, Fred! I will look in those directories once I get home this evening and see if that was the cause of my error message and rectify accordingly. QU eventually locked up and closed yesterday and I restarted the computer. Thank you (and Mike) for all your support and great product!!

I'm repeatedly getting a "Write access denied" Error message while navigating through print options. I may have unintentionally reassigned a default directory a week or so ago while trying to save some settings, but this seems to be new. The attached jpg is the message that pops up. Any suggestions as to how to get things back to normal?
THANKS!

Oh, okay. When you say print quality, I take it that’s in reference to the pulldown menu with High, Standard & Draft selections in the driver (Canon P-10)? I get it. Thank you for the explanation! Your software is awesome!!!

I notice there are two profiles for Canon Pro Luster (Canon PRO-10 <LU>3 [CNBBEUC0.ICM] & Canon PRO-10 <LU>1/2 [CNBBEUA0.ICM]) and likewise for the <SG> paper. The Canon profiles only list one profile each in the drivers\color folder. Is the #3 profile an updated profile for these two papers? Other than a test printing with each profile/paper, can you help direct me in choosing the best profile? QiU chooses #3 when "suggest" is selected...