Day after day, sitting (or maybe standing) at a desktop or laptop can generate a lot of muscle and joint stress. Anything less than perfect posture is a recipe for pain. Head position, elbow support, spine and pelvis posture, position of thighs and legs all come together when setting up a posture-positive work space.
Working at a computer for long hours is kinda like taking a long hike (without the fresh air). You need proper equipment. For the hike, you need good shoes and maybe hiking sticks for rough terrain with a heavy pack etc. For computer work, if you're going to sit for a while you need a good chair. A good chair should have arm rests that adjust to your body and a seat that has a depth adjustment for your thigh length. Looking for a new (or like new) chair? These two office furniture stores have an excellent selection: http://mosercorporation.com/officefurniture.htm https://www.cousinsfurniture.com/ and great customer service!
This is a MUST SEE video on how to set up your computer. It shows everything you need to know for desktop or laptop set up: https://www.youtube.com/watch?v=aLY03KrcpKI (5 minute video)
Do you use a standing desk? Please check out this video: https://www.youtube.com/watch?v=iPFUKbipJHs
For elbow position look at the pictures and note how the arm rests support the weight of the arm and shoulder. This is more important than supporting the wrists.
Now, sit with your spine upright, neither leaning forward or backward with your low back supported. This is the best for your spine. If the seat is too deep, this is not possible. A person with shorter thighs needs a chair that adjusts for seat depth. People with shorter lower legs may need a foot stool. If the chair is set real low, it may be too low for proper arm positioning, so the fix is to raise the floor (with a foot rest).
To work long hours on a laptop, it should be raised up so the top of the screen is level with your eyes and use a separate keyboard and mouse.
Thanks for reading. Put these suggestions to work for your health.