If you sign it, I suggest you buy it in official website, or you can ask them to sign it when you meet the youth league in reality. But don't trust Pinduoduo and Taobao. Most of them are printed and belong to Zhou Ye.
A hand sign is a hand sign. Signing is writing your own name. At the same time, it also shows a person's identity and unity, and a person can assume this responsibility or obligation.