How the hell does one.........?

The three non-digital watches all need new a battery.
The last time I had a jeweller change a battery, I almost had to re-mortgage the house, I don't remember exactly but it was crazy expensive for a $3 battery.

How does one get the backs off these things to change a battery?

YouTube University helped with two of them, but the third....
Looks like a trip to the jewellers is on the horizon.


Ah well...