I recently visited a friends house and used his computer. I went to YouTube and noticed that he had m many more videos displayed on his homepage than I do. Whereas I usually have 2 rows and 4 columns (of videos suggested for me, opposed to recommended) he had something akin to 8 rows and 8 columns.
I cannot for the life of me determine how to achieve this. I've trolled all the settings I can find and searched Google but nothing seems to relate to this.
Whereas I usually have 2 rows and 4 columns (of videos suggested for
me, opposed to recommended) he had something akin to 8 rows and 8
Look like Youtube suggestions page (aka www.youtube.com front page) organizes thumbnails and left menu based on the browser window width. Extend the width - you may get more columns, though at some point the site may start showing you bigger thumbnails too; plus it looks like they are changing and experimenting with the layout all the time. More technically this behavior is controlled by ytd-rich-grid-* CSS class and besides browser window width also depend on scale factor, and probably internal system scaling as well.
At the moment I've tried this in Opera and decreasing scale factor (zoom) in the browser does increase number of columns, though I had to Ctrl+scroll it down to 50% and below for new columns to appear.