Newly Adopted Biting Lhaso Apso

Question
Hi I have just adopted a 2 year old Lhaso Apso called Buster today, I collected him this morning, he has been fantastic all day, very affectionate, following me around for reassurance, lovely with whomever he met. Unfortunately I brought him home this evening and he bitten 2 people, Me, and my friend twice and tried to attack me a second time.
Then he wouldn't come near me afterwards, he sat at the back of the sofa for ages, then came out to see me and has been fine since, he seems more nervous now which he wasn't earlier in the day.
I have walked him about three times today, he is a pleasure to walk. Is he just trying his luck and seeing how far I will be pushed or is this the beginning of an aggressive dog showing his true colors.
The adoption home I got him from did mention aggression towards other dogs but not people, I assumed just bad socialization for this, yet whilst on his walks he hasn't been aggressive to any dog we met, very interested but not aggressive?

Can you give me any advice?

Kind regards

Buster and Kirsty

Answer
This sounds like a dog that is trying to take charge,and has been allowed to do so-and now is the time to end it

The only way to fix this is to call up several trainers,and explain the situation,and go with the trainer that gives you the best answer

This is serious and is best to be dealt with now,rather than later and a trainer is the way to go,as they can show you the steps on how to stop these problems