forum account

I'd like to understand how many accounts should a Xiaomi user have and how the interoperate each other. On my device (pocophone f1) I have an app called MIUI Forum. I've registered there with a chosen user name and Mi Account ID. As I tried to register on the xiaomi.eu/community with these...

I changed even the email but still I get the old mail name on display in my profile. I can see how to change the avatar but not the name.