Change of interface under ‘write a post’

Hello,

This is my first post and I am a little bit stuck using Word Press. I run a small information source https://www.carbonneutraltourism.co.uk

Since yesterday when I go into write a post there is a new interface where under the space where you input the title there is a line of commands which include b, I, link, b-quote etc. I was wondering how do I switch back to the old view of this interface as I am not too sure how to use these commands when writing the post.

Many thanks for all your help.

Kind regards,

Richard