With the '-' and '+' button you can step down and up with the Strong's number. The SR button will show you the Greek (or Hebrew) words with this Strong's number in the Search Results.
ISA3 basic is standard equipped with the Strong's Lexicon. It is also possible to create your own Strong's number based notes in the pro version.
Text size or zoom in/out is independent from the other panels. You can do this by holding the ctrl key while using your mouse wheel with the mouse above the text field. Or use ctrl key with '+' or '-' key (lexicon has to be the focus first - by clicking the lexicon text field).