When dragging a file to another folder with the mouse, the file is copied instead of moved

You're dragging files between folders you believe are on the same drive, but File Explorer copies instead of moving them. First verify both locations' full paths and volume letters; libraries, Quick Access, OneDrive, mapped folders, and junctions can look local while targeting another volume, where copy is the default. During the drag, watch whether the tooltip says “Move to” or “Copy to.” Ensure Ctrl is not being held or stuck, because modifier keys can change the operation. Try right-button dragging; Windows will display a menu where you can explicitly choose Move here. For a dependable workaround, select the files, use Cut, open the destination, and Paste. If ordinary same-volume folders still copy, test another mouse and keyboard, restart File Explorer, and repeat with two new local folders. Avoid changing registry drag-and-drop values until both paths are confirmed. Share the paths if the behavior continues.