[No one]

Isn't it an apparent guess the fluid should be changed? Some even warn if you postpone that too much it can cause trouble instead of fixing. FWIW

Here are some links I found, just for example:

1. a local discussion here;
2. Seven Signs Your Transmission Needs to be Serviced;
3. When you should or shouldn't change your automatic transmission fluid.

There's plenty more to find.