If anyone is still having their YouTube channel crash (no matter what Roku Device or Version you have), this may finally be an answer for you:
1) The Core issue on all of my Roku's proved to start with my official Roku Account here at roku.com where all of my Roku Devices log into a single account. When someone in our family is using one of my devices and adds a new channel, that new channel gets added to all of my Roku devices because they are all tied to the single account at roku.com.
If my wife adds a channel on her Roku 3, my Ultra Roku (when I refresh or check for updates or restart) will show her new channel on my screen, but at the bottom of my channel list.
If she moves her new channel up her home page so it appears near the top for easier clicking, then my Roku will not show she has moved the channel up and I can choose to move any and all channels on my home page without changing her home page.
But the point here is . . . if you have more than one Roku device all under one account at roku.com, then they will affect each other when reaching the MAXIMUM number of channels that a Roku device can handle, leading to a crash on selective channels.
Solution 1: Leave all Roku Devices in one account, but REMOVE/REDUCE the number of channels (which is what I did in the next step).
Alternative: Separate all Roku Devices into their own separate Roku accounts if you do not want one device affecting another.
2) On the oldest Roku 3 device that was crashing, I removed YouTube and YouTube TV right away. I then reduced my remaining channel list from 225 down to 65 channels (with my wife agreeing to which channels we for certain wanted to keep), and it took me at least 30 minutes. There were times when I had to refresh the home screen in order to get the option to Remove back up, as I was moving faster than the Roku was used to. I then proceeded to do the following:
3) I then Restarted the Roku, guessing it needed to clear anything of old content. I know there is another method of "clearing the cache", but I chose just to restart. Also, I chose not to power off and power back on. I just did a simple Restart from the regular System Menu.
4) After the Restart completed, I then went back to System Menu and Checked for Updates. Because the remaining 65 channels were not disturbed, nothing was noticed in new updates.
5) My last "step" was to freshly install the YouTube App. After it installed, I clicked on the option to Launch the channel. The next thing my wife and I cheered at was the successful launch of our YouTube Channel!!!
Summary: I have poured over hundreds of comments on the forum and have read a lot of tips, suggestions, and even some narrow solutions that only worked for a few folks. But in the end a thought came to me that this might be because of an over-loaded "hard-drive", like the ol' days when we were using 20MB hard-drives in PC computers in the 1980s - and the whole PC would lock up - not because the operating software was not working, but because we tried to save everything to a little ol' tiny hard-drive. Our new PCs have gigabyte and terabyte monster drives, but for whatever reason it looks like Roku devices and the use of a single roku.com account sharing with multiple devices - may have led to an overload when we reached 225 channels. Hard to really say, but the above worked for me.
Please share your thoughts and experiences. I'd love to see at least one Roku user post in this topic that the above steps worked for their household too. If not, then I guess I really am the Man in the Moon by myself.