How do I change my user name please?

[tropical1]

Hi, I've tried to change my user name but it doesn't let me! When I type in a new name into the user name box, it immediately goes red before I've finished typing it in.
Can I have idiot proof instructions please??
I've tried on my phone ( not app though) and pc.
Thank you 😀

Try going into this www.mumsnet.com/member/registration-details. You can change your user name here. Maybe you're trying to use a name which someone else already has though?

And ignore the red!!

Thank you!