Any way to make a bigger scroll bar in flow mode?

I find YACReader otherwise excellent but I use it at 4K on a 65" screen about 10' away and my eyesight is poor so I have trouble clicking on the scroll bar so I can quickly jump forwards/backwards on some of my comics. Some of my CBR files are MASSIVE (3500 pages) and I need to sometimes jump to certain sections with more ease. The scrollbar and its button is so thin at 4K it's sometimes difficult to click on (I do get it in multiple attempts but there must be something easier). I read my CBRs in double page mode. Is there any way to make the scrollbar in flow mode taller/fatter or make it scale better at 4K?

Also, is it normal to have the mouse cursor in full screen mode jump to mid-screen if I move it too fast to the bottom? It does that for some reason. Thank you.

There is no way of doing it, I'll see if there is anything I can do about it.

The cursor only jumps if you use the shortcut for showing the flow. It jumps inside the flow to avoid hiding it as soon as you move the mouse.

Yeah, at 4K (2160p) the scrollbar and the button used to quickly drag to pages with mouse cursor is really small and very hard to get the cursor precisely on the button to drag it ( i.imgur.com/8Ek8J9T.jpg ). That would be so great if you could somehow make it bigger.

I found that if I use the shortcut key to bring up flow, the mouse cursor doesn't jump to the top so at least that problem is licked.