What computer operating system is your Premiere Elements 12 running on? If you have not already, please update to 12.1 via the project's Help Menu/Update.
In Expert workspace, go to Publish+Share/Computer/Audio and select the preset there....
Publish+Share/Computer/ offers several choices. But, you do not use the Scroll Bar, you will not see them all.
And, Audio choice is at the bottom of the list. If you do not use the Scroll Bar, all that you will see will be
Adobe Flash Video, MPEG, and AVCHD.
Please let us know if you are OK with this information.