Many dogs are timid. You need to gain its trust. Do this by talking in a calm manor. Don't make any fast movements or yell at your dog. Playing with your dog is a great way to develope a bond and trust with your dog.
It's not abnormal for dogs to be scared of their owners. It's always a good idea to try and interact more with these friendly pets. You can also give him treats and play with him.
Make sure you are always gentle with the dog. Make yourself smaller (crouch or kneel) and move toward it with treats. Give it lots of attention and affection while it is close to you. Make sure your movements are slow and gentle.