Can't get Preview to open files in separate windows
When I open a file (either jpg or PDF), Preview almost always opens it in an existing window. This makes it extremely difficult to find, especially since I usually have many windows open. The pull-down "Window" menu only shows the name of the first image or file in that window—which means I have to search through every open window and check the sidebar or tabs to see if that's where Preview has mysteriously opened the file.
I have gone to the Preview Preferences menu and ensured that "Open each file in its own window" is checked, to no avail. I have closed and restarted Preview—no change.
Help!
(MacBook Air 2015, High Sierra, 10.13.6)