I can't clip my optical cable.

Hello,
Even on the wrong forum, I'm going to respond.
It's true that the end of an optical cable is a bit strange!
The connector has a direction, and when the right position is visually found, it needs to be clipped in by pushing quite hard, otherwise the connection won’t be good, even though the sound still passes through the light beam.
Don't hesitate to force it!!
Cheers!