robert_e_bone
I don't know why it is displayed and altered in two different places.
They are for two different purposes.
Audio Driver Bit Depth in
Preferences > Audio > Driver Settings is often fixed by the manufacturer to one value in ASIO drivers. Try a different driver mode to see the drop down in action. This setting affects how SONAR communicates with the audio interface. The settings in
Preferences > File > Audio Data "File Bit Depths" section control how project audio files are written to disk.
Record Bit Depth is the value shown in the Transport module.