File doesn't open in browser in sharepoint any more?

Hey all!

We have noticed recently that our files within Sharepoint are opening differently to how they previously did?

Below is how they currently open (grey to hide sensitive content)

In the top left corner is the blue open button and then you can select open in browser. It will then display the file like below

This is the much preferred way of opening the file. Is there a way to set this as default? Have tried in the library settings and this doesnt change anything. Previously all files opened the second way however I'm guessing a recent update has changed this? 

Kind Regards, Amber