Audacity

Hi Everyone, I am using Audacity to edit voice over for a series of courses I'm creating.  

I was playing around with the Noise Reduction button and now I cannot remember what the original settings were.  Audacity will not return to the original settings :(

If anyone out there is an audacity expert, can you please let me know how you clean up your voice over? Mine currently sounds like I'm in a bubble with lots of background noise.