To expand on the reply from @DBDukes , your Roku channels are attached to your online Roku account, then downloaded and installed to the Roku devices you have linked to that account (add or delete on one Roku, you add/delete on all Rokus linked to that same account).
As long as you don't delete YouTube TV from any of your Rokus, it *SHOULD* install to a device newly-linked to your existing Roku account as well.
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