Thank you Priyanshi for taking an interst in this.
After some extensive changing of options; dispaly resolution and PSE UI dispaly percentage I have the follwoing results.
The launcher app is always workable whatever dispaly resolution.
If I choose native resolution (1366x768) the PS Elements UI is larger than I'd prefer as it reduced the workspace (especially if I want layers column which I use a lot) 200% option does work but makes the workspace even more reduced as expected.
If I choose the windows 'recommended' resolution of 1920x1080 for the machine the UI at AUTO setting the UI is very small but the workspace is great... I can selct 200% but the UI then become larger than AUTO setting with the Native resolution setting of 1366x760 with a subsequent smaller workspace.
On balance i have decided to stay with the win10 recommended HD resolution of 1920x1080 and use some light magnification glasses.
I guess some more option in the PS Elements UI magnification menu might let me choose an in between UI
PS Windows layout and scale settings doesn't seem to make much difference in PSE although it is evident everywhere else. browser, Word, Excel etc