Dollar Tree

I bought some Christmas items on December 3, 2018. On December 17, I was trying to exchange some items but the store manager refused to accept the items. She said that all Christmas items purchased between November 13-December 31 (approximately) are not allowed for returns as it shows on the receipt. I showed her my receipt and she is correct about no returns, but it did not say anything about exchanging, especially when the items were never used or opened. I think they are in violation of my rights as a consumer. Thank you.