TOME: you have to go into Preview to bold or underline. Above the text box, you'll see rows of symbols, including B for bold, and U for underline. If you've already typed the text, highlight it, then press the symbol you want. If you haven't typed it yet, put the curser where you want the text to appear, and press the symbol. The cursor will appear between to sets of parentases ()l(). Type the text there.
Good luck!