I was out of town so I'm still catching up on Olympics watching, some of it with my Roku. The NBC sports app has switched its default back to non-olympics coverage, but once in the app I'm able to switch back to Olympics coverage using the * button on the Roku remote. However I will say that I'm finding the Roku app frustrating to use, as I can't seem to search the channel, just filter by sport, and there's a lot of coverage to sift through.
Also since I was out of town, I looked in advance both in my Tivo guide and on the NBC Olympics website for the tv schedule so I could record specific events. The website schedule had been my bible for past Olympics, but this time it let me down. A lot of the time for the things I really wanted to watch, the recording didn't have actually have the event I wanted. NBC daytime, late night and NBCSN seemed to be the worst offenders.