Did you try to change this part?

However you can create your own views too. I.e. with Form/Viewdesigner. Or you can change existing views ..

Yes but that only changes the current folder. I also had a look at the view designer but could not find anything regarding the coulmn size or if they should be sized in px or %.

Right, px and % is only a setting for landing pages. This does not help in your case.

In recent days I did some adjustments in jsp. But that is a hardcore way ...

One can set it by px or % on the coulmn sizing in the folder view.

I think that "Title" and "Author" would fit best as percentage of in a ratio of 70% / 30% and the rest of the values fits better in px as they don't vary that much.

I gues I will hav to search the .jsp files and se if I can find the one that holds the default values, and then copy it in to the custom properties directory structure if possble.

Subdirectory custom.jsp will contain your adjusted values afterwards. Custom.jsp will not be changed in case of updates (which happen so often )