how can i change my settlement agreement. i got divorce on March 23 of last year, but i dont agree and do not think that is fair that my ex husband

Changing your divorce settlement is not a taxation question; it's a family law question. You may get better answers on that issue if you post the question again using family law or divorce as the topic. As to the issue of your ex-husband claiming a deduction for your daughter in a year that you were supposed to get the deduction under your existing settlement agreement: you can still claim her, if the agreement gives you the right to claim her for 2015. However, the IRS may ask either you or him (or both of you) to explain why you are both claiming the same child and produce evidence of who is entitled to the deduction. If you have a signed agreement that says you are to get the deduction for her in 2015, then that would be what you show to the IRS. If your agreement isn't clear on who gets the deduction, or if I misunderstood your post and your ex-husband is given the right to the deduction for your daughter in 2015 (or in all years), then you can't claim her unless and until you can get a different agreement. In that case, again, you will need a divorce lawyer, not a tax lawyer. Best wishes to you.