Icons in personalized signatures are generally the result of inputting some combinations of letters and symbols (such as a football icon, and inputting this character combination "/sjb/" in personalized signatures will produce a small football pattern).

If you want to make other designs but don't know the character combination to use, the easiest way is to see a nice icon in someone else's personalized signature, right-click your friend's QQ avatar → "View Information", right-click the icon behind the personalized signature at the top of the window, copy it, then paste it directly into your own personalized signature (click your QQ avatar at the top left of the QQ main panel and edit it in the box below the personalized signature), and then save it.

Tip: The icons you see on your phone are all restored to character combinations. You can write down these combinations and then enter them into your own signature.