Hi pewe, and welcome in this forum!
File/folder lists have separated settings and are not influenced (yet) by the themes.
- Open the Preferences (In the “Manage” tab of the Ribbon menu, open “Preferences” which is rightmost button. The preferences window will open).
- In that window, click on “File exploration” in the left tree. Then in the body settings, uncheck “Underline folders” box. ==> that addresses the underline concern.
- In the same window, in the left tree, click on “Colors”. Then in the body settings, uncheck the “Odd lines” box. ==> that addresses the alternate grey lines concern.
I hope this helps you