Copy and Pasting file of same name

It started happening today - when I tried to copy a file into a folder and there's a file already in it with the same name, it doesn't ask me if I want to replace or cancel it. It just adds "1" after the name of the file. ie. pasting a file named "APPLE" to a folder (or desktop) which already contains another (or same file) named "APPLE", it does not ask me if I want to replace it or to stop it just pastes "APPLE 1" instead.

I am sorting pictures on my macbook pro, this is driving me crazy. Any help will be greatly appreciated!