Caption editing and position scale

Hi,

Im just sitting down for the first time with the new captions tool. It vastly improved on the last version. However, I'm having difficulty stylizing the captions. Is it possible to increase the font size but keep the text to one line? I position the text perfectly for one line, but when it goes to two text lines on a caption, the text jumps up the screen, putting out the top line's position and pushing it up.

Many thanks 

Philip