Playback headset level

I am in the middle of a big book recording and suddenly my headphones started playing back my recorded audio at a very low level. I used the slide fader under Effects and was able to raise the level, and upon doing an ACX check on this computer, the recording met all their standards. However, when I saved the recordings to a thumb drive and played them back on another computer, they were badly overmodulated. I did a Rescan of Audio devices in Audacity, and checked on the sound settings in my Windows 11 computer, but nothing changed the levels issue. What could possibly have made this happen, and how can I fix it?

I don’t know what’s causing the low-level problem

There are a few different ways to change the volume…

The playback slider (now “hidden” under the playback meters) ONLY affects playback/monitoring volume.

The Amplify effect boosts the volume of the actual file/data and it shows-up in the waveform.

The little slider to the left of the waveform affects everything EXCEPT the waveform display.

If you saved an Audacity AUP3 project the audio can go over 0dB without clipping (distorting) and you run the Amplify or Normalize effect to bring the levels down.

If you have a clipped WAV file the distortion can’t be removed. (And you CAN meet the peak & RMS ACX requirements with distorted audio.)

 Update on my post regarding headphone volume and resulting overmodulation: After much experimentation, I found that I have to drag the - and = playback volume fader to the right, at about +20db to hear clearly. (I have no clue why this suddenly changed in my version of Audacity, as I previously could hear playback voolume great at the Mid-0 position.) Maybe Koz can shet some light on this? However, I discovred "the hard way" that if I do not return the fader to the mid or O position, before exporting my audio file, that it results in an overmodulation of the audio file. After much experimentation, I finally figured this out and recovered several audio files I previously thought were corrupt. 
Happy recording folks!

Why is your “update” in a code tag? I don’t feel like scrolling miles to the right…

Update on my post regarding headphone volume and resulting overmodulation: After much experimentation, I found that I have to drag the - and = playback volume fader to the right, at about +20db to hear clearly. (I have no clue why this suddenly changed in my version of Audacity, as I previously could hear playback voolume great at the Mid-0 position.) Maybe Koz can shet some light on this? However, I discovred “the hard way” that if I do not return the fader to the mid or O position, before exporting my audio file, that it results in an overmodulation of the audio file. After much experimentation, I finally figured this out and recovered several audio files I previously thought were corrupt.