Q.I Have 2 New Trees. I Planted (4′ Tall With Leaves) 2 Weeks Ago. Have Been Watering Thoroughly As Instructed. Several Leaves
have turned yellow on one of the trees. Should I worry about it? Tree has about 30 leaves and about 8 have turned yellow.

Certified GKH Gardening Expert
Unfortunately, your photos did not come through. I am unable to see the damage. If it has only been 2 weeks and the leaves are turning yellow already, then I would suspect that the tree has been overwatered. The soil must remain slightly moist, but the top needs to dry out down to about 2 inches, very thoroughly. This will ensure that the under soil remains moist, but not saturated. Saturated soils will suffocate fresh plantings.
In the meantime, this article will help you with testing soil moisture:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm