Change all face-up Dragon-Type monsters on the field to Defense Position, also they cannot change their battle positions.
Rulings
Individual Card FAQs
Dragon-Type monsters on both sides of the field are affected by "Dragon Capture Jar".
If "Stop Defense" is activated targeting a Dragon-Type monster, it is switched to Attack Position, but then is immediately changed back to Defense Position since the effect of "Dragon Capture Jar" is continuous.
Netrep Rulings
Monsters changed to Defense Position by “Dragon Capture Jar” may not be manually changed to Attack Position.
Trap|
Continuous