Latest update regarding changing of yellow option is you can use New jewel called JOAH (jewel of Ancient Harmony) it can be Hunt via killing of MOB or via Box of Heaven and more. But changing using JOAH can give you randomized option. so it means if not luck you cant get what is your desire yellow option using the jewel.
another is to use the WEBSHOP.
1.Go log-in your account at www.infinitymu.net
2. Go the Webshop
3. click warehouse
4. and find your set part to change and click the UPGRADE
5. at the top you can see the UPGRADEITEM and click
6. now you can change the set part item by clicking the down arrow button and select your desire yellow option.