Color in the excel

Hi all,

My Excel was light gray-ish (top and bottom) I will include picture. However when I installed new version of the excel my ribbon top and bottom is Green and I do not like it at all, and I am not used to that.

Can someone please hep me to change to be how it was (light-gray).

I have tried: File -> Option -> General -> office theme but there is no gray there is white, dark gray, black, colorful. Even when I change to white my bottom is still green. If someone has any advice please let me know. Thank you