This is the normal behavior in QuickBooks Desktop, @mcd23.

It’s not necessary to use the main monitor to make the feature works.

When accessing a feature, the other window opens to the main monitor. This usually happens every time you open them at first. You can move the window to your preferred monitor and click cancel, and then open a feature again. This way, it won’t show up on the separate monitor. However, you’ll need to do this every time you access QuickBooks.

Don’t hesitate to reach out back if you have an additional concern. The Community team is always here to lend a hand.