If you selected a file name format previously, it will be replaced by the new format you select.
To select a stream:
The stream type is only set for videos that are directly accessed from devices. This setting will not reflect on videos that are stored on drives, workstations, or docking stations.
You can select a stream type for videos that play from devices, as well as videos that are downloaded from devices. The stream type dictates the resolution of the video that plays. If you select Primary, videos play with higher resolution, and are usually large-sized. If you select Alternate, videos play with lower resolution, and are smaller in size.