I changed positions between Contents (moving to top) & Announcements (moved below Contents). Now my Announcements are below the right column items. Why did this happen?

You're most likely using Firefox. Possibly Google Chrome or Safari, but I'm going to guess Firefox. Firefox doesn't like things that are too wide for the space into which you're inserting them. In this case the issue has nothing to do with the sort order of the Announcements on the page, but rather your text:

We will not extend this discount again.

I'm not sure how you did it, but somehow you had a hard space between each word above rather than a regular space. This gives the system nowhere to wrap the text, blows out the Announcement Board, and in Firefox causes your Announcements to jump to the bottom of the page (the first place on the page where they will fit correctly). I changed the hard spaces between the words to regular spaces, now the text can wrap, the Board no longer blows out, and Firefox displays the Board where it's supposed to be.

By the way, if you have spacing issues again like this, try deactivating your Announcements one by one until you find the Announcement that's causing the problem. Once found, scrutinize the page and/or source code to see if you can find the element on the page causing the problem.

What's the difference between a hard space and a regular space? I'm confused.

Basically, a regular space can wrap. And a hard space can not. The minute you press your space bar two times in a row, you've now added hard spaces. If you press the space bar 50 times in a row, that's the same as putting in 50 characters in a row, such as ttttttttttttttttttttttttttttttttttttttttttttttttt. If you do that too many times you'll eventually blow out the page.