Hello!
When you change your name on manacube you do lose all of your plots, gems etc. Unfortunately Gems, scramblers, hours etc can't be moved to your new name. However, you can get your plots and ranks/titles (If you had them) etc. back. To get your plots back you can ask a mod and provide them with your old IGN, and for ranks/titles you can reclaim them on the websites shop (
https://store.manacube.com/category/688884 ) and clicking "Claim package"