[AppyPappy]

Remember in Empire when Obi Wan said that Yoda was his old teacher? No sign of that in the new series.

Remember in the Clones when Yoda was teaching all of the child Jedi's?

[Aggie Mama]

Yoda was obviously the Master of the Jedi Masters. It makes sense that he would instruct them all. All of the Jedis seem to defer to him.