My Portfolio Sidebar View

I have been using the My Portfolio feature for some time, on a desktop Mac, in Firefox. It normally displays to the left of articles, news, and other content; let's call that "sidebar view".

Today, I accidentally clicked on the "expand view" and was taken to a page that has "My Portfolio" with more columns, lots of detail, takes up the whole page, news and articles below.

OK, great. Interesting. Noted for future use. But since I want to go back to the "sidebar view", i close that and return to SA. I click on "My Portfolio" expecting to see the usual sidebar. But lo and behold, I am once again taken to the full page "expanded view".

I have searched high and low on that page and cannot see a button, link, or other prompt to "return to sidebar view", or "collapse view", or "standard view". I logged out and logged back in. No dice. How do I restore the page so that My Portfolio sits on the left, as it did before?

Is this a one-way street?

Cheers