How to expand vhdx disk VM on failover cluster

Hi,

I want to know the right way in order to expand a VHDX disk of a VM running on a failover cluster of 2 nodes. The nodes and the guest OS are running Windows Server 2012 R2. 

I know that is posible to expand it online (with the VM running) but when I open the VM settings configuration page from Hyper-V manager, it says "some settings cannot bemodified because the virtual machine wasrunning".

Thanks in advance.

Cristian L Ruiz