@astridmp- When you set up a Roku account it gets "branded" with your country or region. Channels may only be set up to distribute programming to certain regions due to licensing or other issues.
Your original Mexican account may limit your ability to receive programming in other regions.
The way to get your Roku set to a different region is to do a factory reset and set it up all over again, this time linking it to a new Roku account (using a different email address) which will be branded with your new location..
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X