Kept in a refrigerator? Surprised they are alive at all.

The crickets are too big - go 1/2". Dust the crickets with a calcium/vitamin supplement before feeding to gecko.

Like your terrarium.

120ºF is a gecko-frying temperature. Their basking spot is best 88-93 F.

Recommended book: Day Geckos In Captivity, Christenson. Best price at Amazon.com; and Geckos, Bergman. If you read German there is even better.