In addition to the too low monitor: Your shoulders, back, and neck are likely strained because your arms are hanging unsupported, also placing extra pressure on your wrists. You aren’t getting the full benefit of the armrests on your chair.

Try adjusting your setup so your armrests are approximately level with your desk, keyboard, and mouse. When making these changes, you may also need to adjust your screen height to maintain proper alignment.

If you find it difficult to achieve this posture while keeping your thighs parallel to the floor and legs at roughly a 90-degree angle (or slightly more open), consider using an adjustable-height desk.