You probably configured some streaming service. Many streaming services recommend or require some audio bitrate, and OBS will enforce that bitrate on audio track 1, because track 1 is the track used for streaming. To stop this from happening, go to settings->Stream and unconfigure any streaming service or activate the "Ignore streaming service setting recommendations" setting.
You probably configured some streaming service. Many streaming services recommend or require some audio bitrate, and OBS will enforce that bitrate on audio track 1, because track 1 is the track used for streaming. To stop this from happening, go to settings->Stream and unconfigure any streaming service or activate the "Ignore streaming service setting recommendations" setting.