GPU in Google colab

I am trying to run my model with Google colab and make use of the GPUs. Can anybody indicate how to activate the GPUs?

Thank you in advance.

In the menu bar at the top there is an sub-menu called runtime. Inside this there is the option to change the runtime. You can switch to GPUs there.

Thanks for your response.

Unfortunately, I am facing trouble in enabling the GPU with Theano. Any advice about that?