In yu-gi-oh, can I activate my monster effect during both my turn and opponent turn?

Question

In yu-gi-oh, can I activate my monster effect during both my turn and opponent turn?

Answer 1

Depends what monster. eg

Exile force cannot activate his effect in your opponents turn

Injection fairy lilly can boost her atk in yours and your opponents turn.

Answer 2

no only on your turn if it doesn´t stand on the card

Answer 3

you can activate your monster effect only if you have a trap card or a spell card on your opponents turn. you can activate your monster effect on your turn only if your monster is face up on the field.