Q: Change phone because of the color

Typically Apple Stores in the U.S. will allow you a 14 day exchange period.

Did you buy your iPhone within the past 14 days?  Did you buy it from an Apple Store or Authorized Apple Retailer?  Did you buy it in person or online?

If it was purchased less then 14 days ago, you can return it to Apple for a full refund.

If not, you are going to have to sell and then use the proceeds from the sale plus some additional case to purchase the new one in a different color.

Is the color that important? It would certainly be easier to just learn to live with the old color, I think.

If you purchased the phone from Apple, you can return it within 14 days and get the color you want. If you purchased it from someplace else, you'll need to consult that retailer for their return policy. If you've had the phone for a while, you can sell it and use the proceeds toward the purchase price of a new phone.