FM Presets on iTouch Clone

[kailess]

I bought a 4 gb iTouch Clone off of eBay like this:

http://i8.ebayimg.com/01/i/000/d6/e1/76a5_2.JPG

How do I save an FM channel on my presets?

My choices are:

- Manual
- Preset
- Mem
- Delete
- Auto

What is the difference between "Preset" and "Mem"?

I'm not sure what each feature is supposed to do. I keep trying the buttons and can't tell that anything is happening.