How do I handle problems selecting and changing font sizes in Yahoo Mail Beta?

Thinking that it may just be a glitch with the Beta version, I switched back to regular Yahoo Mail, only to find the same problem there Here are the problems: 1) The selected text will not always change to the font sizes indicated. 2) I have to select a one or more sizes larger than I actually want, to get the correct size. 3) Sometimes I can't even get the desired font size using the last method. 4) there dose not seem to be as much of a problem going to a smaller font. 4) Once there is any text in italics, everything that follows appears in italics, whether I want it to or not! And, I cannot change the (unwanted) italicized text to regular or bold at all.