Undo tabs not highlighted

I am attempting to make a podcast on audacity and the tracks that I had were mono track then audacity shut down and then it recovered the tracks. After the recovery I tried to make a stereo track so they could play after one another but it did not allow to click “make stereo track” and it was not highlighted. I then clicked “split and render” and then I wanted to “undo the split and render” but it is not highlighted so I can’t click it. Then I thought “split to mono” would change it back to its original track but the undo buttons are also not highlighte.

How do I undo the split to render and split to mone if they are not highlighted options?

After that, how do I make a stereo track if that option is not highlighted?

What version of Mac OS X and Audacity? See the pink panel at the top of the page. I would make sure you have the latest Audacity 2.1.0 from http://web.audacityteam.org/download/mac.

Make Stereo Track joins two mono, left or right tracks on top of each other, not end to end. To join tracks one after the other, do COMMAND + A to select all the tracks, then Tracks > Align Tracks > Align End to End.

Audacity made by us has “Tracks > Mix and Render”.

If menu items are greyed out, press the yellow Stop button.