How do you turn the CX gate upside down on ibm-q-experience?

Just to add. If you do not have a possibility to switch control and target qubits, you can implement "upside down" CNOT with this circuit:

$$ (H otimes H) CNOT (H otimes H), $$

where $H$ is Hadamard gate and $CNOT$ is controlled NOT with control qubit upside and target qubit downside.

If you click the CX gate itself, it will be surrounded by a dashed box with a pen symbol in the top right corner.

If you click this pen you can choose which qubit is the target and which is the control by drag-and-drop.