Why can't I change my email address at Mojang?

Attention!
Your account has not been secured. Securing your account will help protect you from unauthorized use of your purchased Mojang Studios games.

https://account.mojang.com/.../me/secure

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Realms Subscriptions
Minecraft Realms is our subscription based service for hosting your Minecraft worlds. https://www.minecraft.net/...net/realms

Note: Realms purchases and management has moved to https://www.minecraft.net/...ile/realms.

I think you have to press "https://account.mojang.com/me/secure" and then, as far as I know, there are security questions that you have to set and remember, for example, if you want to log in with a different Ip or something, then I think the security questions that you have to answer come, so keep it well ^^

Thank you for your answer, but I've already tried this and I've come back to the same page