That's strange.  In the example below, I've created a similarly distorted rider and circled the rider anatomy values I needed to change in order to make the body look that way.  If the rider anatomy values were not changed before the model was saved, there is no reason the body should appear this way upon re-opening the file.

When you have been saving and opening the model, have you been using File >> Save and then File >> Open design from BCAD file or File >> Open recent BCAD file?  These options will save or read in the entire model including the bike and rider.  Meanwhile, another option would be to save and open templates.  Templates are described at: bikecad.ca/templates_in_bikecadpro.  If you save a Bike template, you will only save the bike design itself, not the rider.  When you save a rider template, you will only save the rider geometry, not the bike.  In turn, when you go to open a bike template, you will only be reading in the bike design, the rider geometry you currently have loaded in will remain the same.  If you read in a rider template, you will be reading that rider's geometry into your current model.  This doesn't explain what is happening with your model, but I mention it in the off chance that there is any confusion over the use of templates.

Assuming this issue remains unresolved for you, I would be interested in seeing your BCAD model.  Could you please e-mail it to me?