@ohanquels
There is no device-wide setting that can enforce data usage restrictions. Such functionality did exist in the early days, but with today's streaming technologies, those old settings won't work. They were never official anyway, but for testing, though they did leak to the public. But know that if anyone suggests those, they are not officially supported, and may not work (and probably won't, given today's technology). So what can you do?
First, pick the lowest resolution setting you can from your Roku menu system under settings.
Next, within whatever apps you intend to use, change the settings either within the app or within the service account (often via Web browser) to the lowest data usage/resolution they offer.
Finally, if the service or app allows, turn off autoplay. You don't want them launching something then walking away and leaving it streaming the next episode/cartoon/whatever to an empty room.
DBDukes
Roku Community Streaming Expert
Note: I am not a Roku employee.
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