4K monitors were not widely available when Elements 12 was introduced and the GUI was not scaled for it. Even the latest versions of Elements have some limitations for display on a higher resolution monitor. I don't know whether it will help with your version, but try using the Windows>Settings>Display>Scale and Layout settings. You can right-click on the desktop and get to it via Display Settings in the context menu.
Later versions of Elements do have a high resolution display setting that can be changed between 100 and 200%. This usually helps most folk with a 4K monitor.
I tried Windows Display Settings and changing those settings doesn't really help. I trieed changing both resolution settings and scaling, to no effect. As you explained, it's probably the legacy issue with this older version of Photoshop.
I may have to try Elements 2021 after all, although I tried to avoid it and stick with what I am used to.
Thank you for taking time and responding to me question. Appreciate it!