Yes, I just realized that too, it has to be a minimum of 10 posts.

You can go to settings page on that you have an options of edit signature you can put your signature different form have different number of post limit to get the signature

Go to User control panel and there you can add signature.

how to add signature ?
 

Create a signature
On the Message tab, in the Include group, click Signature, and then click Signatures. On the E-mail Signature tab, click New. Type a name for the signature, and then click OK. In the Edit signature box, type the text that you want to include in the signature.