Previous File in Directory
Click on the View Menu, then click Previous File in Directory (or use the Previous File tool on the toolbar). The viewer displays the previous supported file, in reverse sequence.
You can also use the Backspace key to move to the previous file in the directory. If the image does not have a vertical scrollbar at its right edge or you have enabled the appropriate property option at Browsing/Editing, you can also use the Page Up key or roll the mouse wheel up to move to the previous file in the directory.