Having fresh line is one of the most important aspects to the sport of fishing, so any tip to help make the chore easier is a good one.
Here is how I often changed line during my years of running sportfishing boats. It makes it a one-man job and works well.
Here it is pictured in the cockpit of a boat, but you can rig it to do at home as well. I built a small stand with a rod holder in it for home operations.
Take a five-gallon bucket and drill a hole near the top in both sides to hold a dowel of any sort. I fix a wire tie or similar stop on one end of the dowel to keep it from walking out of the hole. Fill the bucket with water to slow the spool down and wet the line to help it pack down on the reel.
After the spool is in place in the bucket, I use multiple wraps of a rubber band to create the removable stop on the other end of the dowel. This will prevent the dowel from working out of the bucket as it spins.
Next thread the rod and tie to the spool of the reel. I use two wraps around the spool to help it grip and not just spin inside the loop. I use a uni knot and trim the excess tag.
Now take a small line and tie the rod down into a bent position. This makes an unbelievable difference to the whole process as it steadies the rod and takes the bounce out. Just slight pressure, nothing crazy.
Now with a smooth cotton glove that I wet down to keep it cool, I pass the line over and under a few fingers to help apply pressure as you crank it on. Work your fingers to find the right amount of pressure and fill the spool to the desired level. Occasionally you may have to refill the bucket with water as the spool slings it out.
Once you are set up with the tools for this, you will be able to do multiple rods in short order.