I've been using Excel for Mac 2011 since it came out. Up until I updated to Yosemite, formatting negative numbers with parentheses appeared in the drop down menu, i.e., right click to get format cells, click "number" tab on top, click "number" on left. There is a dialog as to how you want negative numbers formatted. Parentheses used to be an option but no more. I attached a screen shot. Help!