system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why didn't Yoda share the secret of becoming a Force Ghost with other Jedi besides Obi-Wan?
gpt
Qui-Gon is the one teaching the force-ghost technique, not Yoda. At the end of Episode 3 when they are going to part ways Yoda says to Kenobi that during the exile time an old friend will teach him. Qui-Gon died before mastering it and he has only a voice but Yoda and Kenobi had more time and by the end of their lives they were probably more powerful and in peace than Qui-Gon.

The last three episodes of Star Wars The Clone Wars touch this subject too.

Edit. So in essence, by the time Yoda was able to teach the technique he had no time to pass it to fellow Knights and Masters.