Once you get the settings the way you like, you should be able to click anywhere on the screen and then press the play button and here what’s at that current position.
If it’s not what you like, try the undo function and give it another shot. I know it can be frustrating and time-consuming but I’m not sure there’s a better way.
The only thing I use Audacity for is converting my vinyl records (using the ION turntable) to MP3s on my computer. I bet there are sites dedicated to questions like yours. Although Free Republic is frequented by lots of computer geeks, it’s not really oriented towards rather arcane tech questions such as yours.
Good luck.
Read the help file and tutorials. Auducity can do a lot of complicated things for a free program.
Not sure if I understand what you are trying to do, but have you considered making your selection a separate track?
You could then modify to your heart’s content and simply position it when you are done.