Windows 10: some questions about 'about:config'

Basically I see wider scroll bars everywhere except MS Edge. Examples:

CCleaner





Vivaldi

 

Oh! You're talkin about the system wide tweak!
Here I am goin on about the .css tweak for Firefox only!
Okay, gottcha! *Thumbs

 

I think my problem of trying to increase the width of the right hand-side scroll bar in Palemoon as well the the font size in the bars at the top of the window appears to have been solved. I can't remember exactly where I saw it but someone either from this site or another one mentioned a programme called Winaero Tweaker which not only contains numerous 'fixes' of how to regain the looks of W7 and earlier but also of how to increase/decrease the sizes of fonts and scrollbars which have been omitted from W10. I went through the programme, made a number of changes but nothing seemed to happen at first until yesterday when I turned on my computer and noticed that both my fonts and scrollbar were larger. I had also followed the advice given by Edwin & Callender re. the register and about:config but I'm not sure which of my 'clicks' within the reg. or a:cfg. or Winaero contained the right trigger, suffice to say that my scrollbar is now between 4 and 5mm wide ... big difference! ... and I am now able to see the words much more clearer at the top of palemoon (and other windows).
My thanks to Edwin & Callender and to whoever mentioned the Winaero programme ... very much appreciated.