My file is 44.1 as AUP, however when I export to MP3 it is 44.8. This is not ok for ACX so I attempted to export a new MP3- got the same results. Under preferences I have Quality-Sample at 44100. AM I missing somewhere else to change it? I have not had this happen before.
Changing it within the MP3 file under the Audio Track- just totally changes the voice so that didn’t work either.
Using Audacity 2.3.0
Thanks,
The sample rate of the MP3 is taken from the “Project Rate” lower left corner of the main Audacity window). If “Project Rate” is set to 44100 when you export, then the MP3 will be 44100 (unless you select an extremely low bit-rate, in which case you will be prompted for a lower sample rate).
Well Crap! 
I looked all over the place and did not see that down there. I think that fixed it…thanks so very much…I have over 10 files that I did this to!
’
You have made my day so much better 
Could you have meant 48 rather than 44.8? 48 is a perfectly normal video sound standard. 44.8 could be a typo.
Koz
Koz- I did mistype but Steve helped me fix my error so all is good now!
Thanks,