How do I change the date on my eco drive ladies watch purchased yesterday t costco

The turn dial on the left side of the watch pulls out ever so slightly to loosen it so it can be turned. Adjust your time and then push it back in to set the time. You need to use your thumbnail to get under the dial to extend it. One note about your watch: since it's solar powered, you need to make sure that it gets exposed to light. Don't put it in a drawer or jewelry box, and keep in mind that in the winter when you're wearing long sleeves, the watch is not exposed to light. This will deplete your battery to the point where it will no longer charge. Since you've purchased it from Costco, the service on it is excellent. I've had mine for several years and except for the above-noted battery issue, it's been great. Had a service repair, they replaced the battery, and crystal, tightened the clasp, and it's been like new ever since. No one wants to lose their contract with Costco so the service on products they sell is always outstanding. Hope you love your watch as much as I love mine.