I can't change the font size of a link in my implementation of the YUI Editor. I believe I'm using version 2.9.0 but I don't see that as an option in the version drop down so i left it as 6.x-2.33. I replicated the problem in the following online example:

http://developer.yahoo.com/yui/examples/editor/flickr_editor.html

Using FireFox 3.6.11 I went to the example page above and highlighted the last word and made it a link. I then highlighted it again and tried clicking the font size spin button's up or down arrow. The value immediately sets itself back to 13. The same thing happens if I try to change the link's paragraph style.