Answer:
I am a protector. I sit on a bridge. One person can see right through me while others wonder what I hide.
Where do fish keep their money?
I roam through the lands hoping to rescue my love. I search high and low and will stomp on you if you get in my way!
Sometimes I annoy you, sometimes you can't live without me. But no matter how hard you try, you can't destroy me. What am I?
I begin your sentences. What am I?
No matter how little or how much you use me, you change me every month.