How do I change my ip address in my iPhone 4?

Go to Settings > Wi-Fi > Your_Network > Static (IP Address).

I need to change my ip but it needs to a totally new ip or whatever I can do to keep from getting kicked off of a forum I've been a member of for years . What happend was when I bought this phone and go to the forum in question it says my ip has been blocked forever !!!! And it's not me and the moderators understand this but it must be the guy that the phone belonged to . So when I go to the forum using my iPhone 4s also going threw tapatalk the forum recognizes my ip and it bands me from the forum and I have to start all over again using my laptop ??? And the going to airplane mod for 10-20 min and going back DOESN'T WORK!!! I need a hole new ip address and whatever else I can do to make this phone work on the forum !!!! Please help. Thanks

Sorry, nobody here can change your IP address.

Your IP address is assigned by your internet service provider. For home connections (i.e., cable to your router) it is usually not a static address, it will change periodically. I don't know how AT&T or other wireless providers assign IP addresses; I don't know if they are static. The IP address assigned to you by your ISP is the one the website will see and you cannot give yourself a different one. If you are using a router, your devices may show different IP addresses that have been assigned by your router but those addresses are internal to your local network. The one assigned to you by your ISP is the one the rest of the world sees.

Question: are you connecting to the Internet via cell or via wifi on your phone?

It seems to me that if the problem is with a particular website, the moderators or owner of the website have control over which IPs are blocked and which are not. They can unblock it if they choose to.