I'm a little surprised that in five years, no one has pointed out that changing a watch battery isn't rocket surgery. If you don't already have to tools to open a watch case, you can get a set of tiny screwdrivers or a case tool for a few dollars (Harbor Freight sells a case tool for $5.99).
If you can set a watch, you can change a watch battery.
If you can set a watch, you can change a watch battery.