Leading others at work

Hello! The gal that reports to me at my new job is stuck thinking that she isn’t good enough. She repeats stories and explains every decision that she makes to prove that she is good enough. I already value and respect her and know she is qualified and I have told her that several times. I am trying to move forward with setting goals but she wants to argue every decision instead of letting me lead the way and give vision for goals. I want a team player that feels confident about herself so we can move forward together. Not sure how to help her change her mindset as her boss and not her coach. Is that even appropriate?