Updating Photohop

I am trying to update my photoshop but it doesn't appear to let me. When I click to do so it says to close the photoshop programme but when I close all the files and press continue it still doesn't work and then when I close photoshop all together the continue button goes and I can't do it at all. When i try to update it through adobe it then doesn't come up with the option even though it is still the 2015 model. Really confused how to update it.