I forgot how to turn a3up file to an Mpe file

After recording music I click on “export.” After that I do not remember how to convert the 3up file to a Mp3. I vaguely remember using a right click to make that change. It seems like I can’t right click on the 3up file. Can the answer in sequence steps. Last question - do I save the music file and is the transfer to Mp3 with the save function? Thank you.Thank you

Open the .aup3 file in Audacity.
Click File, Export Music and pick whatever options you want.
You can export entire file , or just a selection, and to MP3, WAV or others