When you record to a new Audio File Project and save for the first time, you will see this dialog:
It may appear that the project will save as 16-bit integer, but this is not necessarily the case. Audio File Projects save at the same bit depth they were recorded. The Bit Depth drop-down is dimmed and has no effect when saving as an Audio File Project. If you choose a different option from the File Type menu, such as AIFF File or Wave File, the bit depth can be changed.