CONVERTER, latest ver., Using "Resolution Scroll" before converting video File

So. I've got videos around 376x220 or maybe a little lower or a little higher & I get lucky, click the "Modify" and yep, there I am, somewhat North of Befuddled and looking somewhat sideways justin case George Carlin shows up. & I begin to wonder:
1) Should I set it to the Closest Listed Resolution on the LOW side of the original ---> or the HIGH side, OR should I just set it to the highest setting.
2) There a few other VERY IMPORTANT settings inside "Modify" also, but it's been quite some time since I'e seen them...

3) Enough chin-waggin'. Now best time to go experiment on that lovely li'l Converter & PUT ALL that 'me-and-der-ring' to unique use. Private reply ---> quikstudy@cox.net