What is up with the font changing in ads?

So this has happened to me a couple of times now. I write my ad in a certain font then when I go to preview proof read my ad it comes out all cockeyed, some of it is the original font then other font appears that is smaller and sometimes the color has even changed, what gives? Then I go back and fix it like what happened last night to my Lake Charles ad and I notice another line where the font has changed. Well I needed to get the ad in by midnight to have it in the correct timeline so I submitted it, then I go back this morning and look at it and some of the other font has changed to even smaller letters. What in the world is going on? It makes my ad look whacky .

Please send me links to the posts in question and I can look into it.