The most common occurrence where PDF files start zooming in when trying to scroll on them in the viewing pane or where you have minimized an action window and can no longer see the little minimized box is when you have a different text size in your display settings. In order to check this please follow the below instructions:
If you are on a remote desktop please minimize it as this will need to be checked on your regular computer.
Right click anywhere on your screen and choose Display setting.
Look for the field which say Text Size and make sure this is set to 100% .
Go back to your remote desktop and test this.
If you are struggling with the above steps or you do not have access/unable to find the settings please raise a new case online and reference the title of this article.