I have a project with 7 tracks. I want to export them to wav files one at a time. I mute all the tracks except the one I want to export. How do I set and end point so that the exported file ends where I want and not at the end of the longest track even though it is muted?? Thanks in advance

All you should have to do is select the desired range in the timeline after selecting the track.   That range will also display in the Control Bar.