White Band Displayed Across Wave Form

Somehow I have turned on a sound-level feature and can’t find out how to turn it back off. There is a white band across the center of the wave form that aligns with the plus and minus 0.5 dB marks. If I grad the edge of the band I can pull the volume up or down. The band was not there when I started using the program, and I can’t find anything in the manuals relating to it (not knowing what it might be called, it’s hard to do a search for it). Can anyone tell me how to turn the feature off? Thanks!

You clicked on the Envelope Tool. Two white arrows and bent blue line. Click on the “I-beam” tool.


Thank you!