Welcome to Yorkie Talk. Yogi is probably accustomed to going indoors on a pad at the breeder's home and may not know that it is okay to potty outside. That was my experience with Max.
Although I intended to continue using piddle pads, I also wanted him to go potty outdoors. It took a couple of months before he figured it out. He would hold it until we returned home from walks and outings. One day, he couldn't hold it any longer and he peed. I praised him profusely and he saw my reaction and started peeing every time we went out. The same thing happened with pooping. He finally couldn't hold it and pooped. When he saw that I was overjoyed, he wanted to poop outside every day.
You won't have to wait 2 months, but you may have to spend a long time outdoors with Yogi. Take him outside the minute he wakes up from sleeping/naps, after meals, after playtime/excitement, and many times in between. Stay outdoors until he goes. Use keywords and phrases to tell him to potty. When he does it outdoors, show him you are really excited and give him a little treat. He will figure it out soon.
