I am not entirely sure I understand what you are asking. You may open the bookmarks sidebar for instance use keyboard shortcut Ctrl + B that will open on the left hand side. Is that something you had seen and wanted to do ?

I know how to open the bookmarks sidebar, but it opens on the right hand side of the screen. How do I get it on the left hand side of the screen?

Try moving the Bookmarks icon to a different menu bar. I did and the bookmarks sidebar opens on the left. The only way I could get it back on the right (which is where I wanted it) was to go into Troubleshooting and Reset Firefox.

Firefox 17.0 is an older version which is no longer supported. You should update to either 17.0.8 if that is the ESR version or 23.0.1 is that is the Release version. Either way, if you open Help > About Firefox a Firefox update check should start automatically, And if it doesn't start automatically, use the Check for Updates button.

As far as the bookmarks being on the right instead of the left. try the Firefox SafeMode and see how it is in the SafeMode.

https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode#w_how-to-start-firefox-in-safe-mode