Use a pair of pliers or strong tweezers to bend the leads on the new potentiometer straight.

Place the new potentiometer onto the board, making sure to pass the locking tabs through the board.

Solder the 5 leads while applying pressure to the top of the potentiometer so that it moves flush with the board while the solder is still liquid.

Since the locking tabs extend through the PCB, it's helpful to place the PCB on the edge of something like a cardboard box while soldering so that the locking tabs are free to extend below the PCB, allowing the potentiometer to be completely flush with the PCB.

Bend the 2 retaining tabs on the other side of the board flush using a spudger tool.

Now is a good time to test that the volume knob and microphone still work before reassembling the case.

If flux was used during the soldering process, it's a good idea to clean it off using isopropyl alcohol or a circuit-friendly cleaning solution before reassembly.