How do I update or refresh the list of Photos libraries that I can choose from when opening the Photos app?

I've recently installed a larger internal SSD in my iMac, enabling me to transfer my multiple Photos libraries back to my Mac from their former location on a dedicated external hard drive. (I also back up my iMac regularly to Time Machine and another external hard drive.) Now, when I option-open the Photos app to choose a library (other than my system photos library), I don't see the alternate libraries on my iMac in the list, only their copies located on my backup hard drive. I can open the desired libraries by clicking on "Other library…" and navigating to their location, but that doesn't seem to change the list for the next time (i.e., the list doesn't show the alternate library as having been the one opened last). How can I refresh or rebuild this list to always show the libraries located on my Mac?