You can easily change the RPC for any of the blockchain networks you are using,
Just go to "Settings" -> "Networks" -> select the network for which you want to change the RPC -> and click on "Edit":
You will see a field, where you can add the custom RPC.
Once the RPC is added, it will appear in the list below.
Note that you cannot remove already added RPCs, but you can switch between already added ones at any time.
