Apple ID verification / out of date email

hi there,

i will try to describe as brief as possible.

After upgrading to iOS 10, my iPhone asks every 10 seconds to for ape ID verification "enter password for...@icloud.com in settings"

but i don't remember the password for this icloud and email connected to it is no longer in use. o created new apple ID with gmail account.

I was wondering if I could sign out from the iCloud in settings and simply add new gmail email a address? Will I loose thing on my phone?

P.S. I wanted to follow steps of temporary change of Apple ID on the acoountpage. But it asks me to change my securities questions and I f in everything and tap UPDATE, but nothing happens and I'm left on the same page.

would be greatful for any advice or help,

thank you