On the LO main startup page how do I change the files that appear from thumbnails to a list format?

No further details to add.

Attention (to avoid a common misunderstanding) These thumbnails represent the *list of recent files used / worked on. It is not an overview list of files on your disk (LibreOffice isn’t a replacement of a file manager at this point).

You can not change it, there is no list format.

If you have many icons and some are not visible, you can scroll down.