Thanks for reaching out here in the QuickBooks Community with your question. QuickBooks Online has a large variety of reports to help you to follow every aspect of your business's books. Being able to bookmark your favourite reports can save you the time spent looking for them. I can see why you'd like to have them appear in two columns, that way they're all easily accessible.
When I tried this, my favourite reports automatically created the second column. However, when I reduced the size of my window it reduced them to one column. Currently settings for formatting the Reports page are unavailable. Be sure to check your browser to make sure the window is set to full screen.
If your reports are continuing to appear in one column, you may need to clear your cache and cookies. When you open websites, they download cookies into your internet browser's cache. Eventually this needs to be emptied or it begins disrupting communication within internet-based programs like QuickBooks Online.
To troubleshoot your internet browser, follow these simple steps: