Over the years I've linked 5 Roku devices to my sole Roku account.
When linking your new device(s) perhaps you missed the prompt to link your new device(s) to your existing Roku account, or maybe you didn't get to the actual Roku link site at all.
IMPORTANT! Note, when you are directed to go to roku.com/link to link your new device, type it in very carefully and verify that you actually do go there. Otherwise you can end up at a scammer's fake Roku site. If you end up at ANY non-roku.com site (other than the https://my.roku.com/link that you'll get redirected to), back out and try again.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Do not ask me support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.". Please only do this if it ACTUALLY solves your problem.
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X | Streaming Stick 3600