On a small display, like an old 1024x768 laptop, some of the settings are inaccessible.
For vertical scrolling, you can't get to the very bottom of the window. And there's no horizontal scrolling, which can also cause problems.
See the screenshot.
To test, just make the settings window too short and too narrow - you don't actually need to use it on a small laptop.
I suspect most jAlbum users are on larger monitors. My own demo site stats show almost no one visiting with 1024x768, but quite a few with 1366x768, like 6%. About half of the visitors are using monitors that are 1920x1080 or larger. So maybe this isn't worth agonizing over.
Those look a lot better. As long as the user can actually get to all the settings, it's probably good enough.
I wouldn't worry too much about the horizontal scrolling issues - even low-end laptops these days have wider monitors, like 1366x768. In my site stats, I see very few 1024x768's. See the screenshot, covering the last few months on https://jgromit.com/. The 800x600's are bogus - they show a bounce rate of almost 100%, which tells me that they're bots of some kind.
Either that, or just get rid of half the options in the skin.
My goodness, what are those people using, they are out of date even 20 years ago? I really have to visit your site more often to get the statistics up a bit. There is not a single entry in your screenshot with a resolution of 4K (3840x2160), let alone bigger. Where are all the Apple fanboys with their 5K screens? Not to mention 8K. This shows once again how wishful thinking of the monitor industry and user behaviour are diverging.
There is not a single entry in your screenshot with a resolution of 4K (3840x2160)...
Number 48 on the list - 3 visits during 2020, at 0.25% - and nothing bigger.
Since the only visitors to my demo site are all jAlbum users, it's a fairly good representation of that community. It's different for "normal site" visitors, where you get more obsolete equipment (your Aunt Minnie, looking at your holiday snaps). But on my "travel" site, over half the visitors are on 1920x1080 monitors. That's why my default settings for image bounds are typically 1600x750 or 1800x900.