JW's don't teach that Earth is only a few thousand years old - obviously you met a couple who haven't been keeping up with Jah's chariot.
Not sure if there's been any "new light" on the matter, but as far back as ten years ago they taught the Earth was "thousands" of years old. In the years leading up to 1975, they taught that each creation day was 7,000 years old, so the Earth was less than 50,000 years old. After the resulting fiasco, the 7,000 year creative day idea stopped being taught in lieu of a generic "thousands of years" response.
Absent there having been some new teaching in the past few years (I haven't been keeping up), there was never really any support for the idea of an Earth that is millions of years old. The picked "thousands" very carefully. They never officially dropped the 7,000 year day. By saying "thousands" it was ambiguous whether they old teaching had been officially rejected.