Unscrew the old connector off the used tank, remove it from the mount or cradle and set the new tank in its place.
Check both the male and female connectors for dirt and debris, and make sure they are clean. Wipe each with a rag if needed.
Screw on the connector to the new tank by turning in a clockwise rotation. Most newer connectors have thumb holds so that they can be turned on and tightened by hand. Tighten firmly.
Turn the gas cylinder on and listen for any noticeable hissing noise. If hissing is coming from the connection, tighten it down. If any hissing is coming form the hose, it will need to be replaced.
Dab some dish soap around the connection and look for bubbles as a final leak test. Bubbles mean leakage, and if the connection is leaking, tighten it down until the bubbling ceases.Wipe off any remaining dish soap and secure the cylinder with the straps or brackets at hand.