There is no way to turn it off, however if you EXIT the YT/YTTV (or any Instant Resume enabled) apps via their UI/Menus Exit options (keep going Back until you get the Exit option then Exit) then that forces the app to fully close and will re-launch normally the next time they are opened.
Unfortunately the "Moderators" are not highly trained/knowledgable Roku employees in regards to RokuOS or hardware (and certainly not third party vendor apps) and lack adequate training/knowledge beyond typical CS recipes/flowcharts/pre-formulated responses/KB usage, and in fact are highly limited/restricted in what they are allowed to post.
So this function is just on the ultra?? I have 4 other streaming sticks and they automatically close and restart the app
Again, the YT/YTTV app versions/builds on the 4850 are using the Instant Resume feature of the OS.
The YT/YTTV app versions/builds for other/older models (different than for the 4850) are not using the Instant Resume feature.
Apparently Google decided that the YT/YTTV app builds for the 4850 would finally support Instant Resume and coded/enabled them as such.
Its entirely possible that the YT/YTTV apps for some older models will become Instant Resume enabled with future updates.
The YT/YTTV apps are operating normally/correctly in all cases, relative to whether they are Instant Resume enabled or not.
You'll need to direct your complaints to Google about the Instant Resume support of YT/YTTV app versions/builds for the 4850, however suffice it to say they are very unlikely change their minds/app behavior.
You do have the option of simply exiting the app using the app UI's Exit option (instead of pressing Home) to actually exit the app, then it will reload as desired (and thats the case with every/all Instant Resume enabled app(s)).
Sorry I started this thing and didn't check back for a while. I skimmed through the various responses to catch up. Since this is a feature being implemented by the app developer, can I request a modification to the feature? I'd like the ability to disable the Instant Resume feature system wide. When I press the home button quite often my next step is to turn off the TV and do something else for a while. When I return I most likely don't want to resume what I was watching before, and if I do I can always open the app > find the thing I was watching > it will resume where I left off via the watch history recording the last played location/time. So I, and possibly some of the others that have responded to this thread, would prefer to have the ability to turn off Instant Resume.
Yes, of course you can request features - of both the app/service provider (Google) and or the platform/OS provider (Roku).
Whether they bother to listen or implement them or not is another issue entirely, with the "wont listen/wont implement" being the case almost always.
A global/OS setting to enable/disable Instant Resume is a good idea (along with other such global/granular app behavior controls), though I will warn you that even if such a feature is implemented it is likely that Roku will allow itself/app publishers to "block" or "disable" (or exempt/limit) the functionality/setting from applying to specific apps (this is based on current/historical policy/behavior for other global setting functionality).