@Taylor810
TL;DR: Google (not Roku) uses different external/platform versions and internal/UI versions for its YT/YTTV apps for different Roku models & YT/YTTV accounts.
----------------------------------------------
External/platform version: Highlight YTTV app, press Options (*):
Specifically, they have 4 external/platform YT/YTTV app version tracks for different Roku models/model ranges.
1) Latest model(s): 2.22 (this version track usually only exists for a short time (1-3 months) following the release of the latest Roku models, then combines with 4K/HDR)
2) 4K/HDR models: 2.22/2.21 (this track includes "latest" within 1-3 months after "latest" release)
3) Non-4K/HDR models: 2.20
4) Legacy models: 2.0
5) Roku TVs: Depends on brand/model - above 4 categories apply
The latest/greatest models get the newest YT/YTTV app version, the 4K/HDR models get the next highest, non-4K/HDR models get the next, and legacy models have the lowest version.
YT/YTTV versions/builds are also RokuOS firmware version/build dependent on occasion (meaning certain YT/YTTV version/builds are only available with certain RokuOS versions/builds; upgrading or downgrading RokuOS can/may/does result in a different YT/YTTV version/build).
However, occasionally models in the latest and/or 4K/HDR categories are inverted/reversed/mixed, such that the "latest" 4K/HDR models have a lesser version/build (2.21 currently), and "older" 4K/HDR models have a greater version/build (2.22 currently) - such is the case currently (e.g. 3810 (2017/2019) has 2.22, but 3820 has 2.21)
Internal/UI version: Open YTTV app, Account/About/App version/Version:
Google also uses a "universal" (downloaded at load time) internal/UI version so that their apps have a consistent look/feel across different platforms; however, the options/appearance of this internal/UI version are dependent upon the external-platform version (e.g. 4K, HDR, Speed).
This internal/UI version can also be dependent on account - Google is testing a newer (soon to be released) UI for YTTV that is only available for some accounts, which is most likely why your son's SS 4K+ YTTV app UI looks different than the YTTV app UI for your SS+ (his YTTV account is "Beta testing" the new UI). Eventually, all accounts will get the new Live Guide UI.
Certain internal/UI version features/functions are only available with certain external/platform versions & models (e.g. Speed settings are only available for 4K/HDR-capable models using YT/YTTV app versions 2.22 & 2.21 - non-4K/HDR-capable models do not get the Speed settings, nor do 4K/HDR models using version 2.20)
