My IPV6 keeps changing

My IPV6 keeps changing
Recently I got the BGW210-700 model modem for Uverse from AT&T since they upgraded my speed to 18. What now I notice is my IPV4 is grey'd out except the gateway is highlighted and the IPV6 IP address is also highlighted. Everytime I try playing WOWS legends
it prompts the message "Failed to connect to server" when I check the settings everything was fine so I resetted the modem and was able to play again. Took a screen shot of the IP addresses.

Next day had the same issue as yesterday, failed to connect, checked the settings and behold the IPV6 Ip address changed resetted the modem again and was able to play. Its getting me frustrated and aggravated that I can't set the static IP for it to stop
changing.

I look'd at a youtube video about setting the static guy said on the video if you set the IPV4 manually the IPV6 should follow.

What do I have to do for the IPV6 ip address to stop changing?

:)