During the process of setting a series recording, there is a section that says channels. You can set it for the current channel, SD preferred or HD preferred. You can also adjust this same setting of a series that was already setup by finding the recording/series under For You/Recordings/Scheduled and the press OK on the title you are looking for. Then go to options and select all recordings. The same screen will come up that you would see when initially setting up the recording and you can adjust the channel settings there.