Hello adminssa,
I know of no way to do that within the ADR interface & settings. Someone more tech-savvy would be able to, I'm sure.
It's a simple matter to change ".WAV" to ".wav" in Windows. It has no impact on how the file plays. If you needed to change a batch of file extensions to lower case, you might want to look into batch renaming software.
Unfortunately, that's all I'm able to offer you.
PIX
PIX YouTube channel