Gradient tool only allows me to use presets

Up until a couple of days ago I was able to create gradients on the fly using the background and foreground colour boxes on the tool bar to set the colours. Now it will only allow me to use the presets. I know I can add my own gradient colours to the gradient menu but it was so simple to be able to do it as mentioned. I could easily change just one colour. Is there any way to return to using gradients this way or am I now stuck with using only the gradients menu?

I am using the most current version of Photoshop CC on a PC. I've checked all the help files and the threads on the forums but nothing addresses this particular issue I'm having.

Thank you in advance.