As mentioned above, the fountain pen icon for the signature turned into a lock icon. I assume that might happened for a particular pdf file which was secured and had some security set up.
There isn't any specific setting that you need to change to use draw feature for a signature, because this is what you get initially when you select pen icon to add signature.
Please refer to the help document to get detailed description of creating signature Acrobat Reader Help for iOS: Creating Signatures and Signing
This might help you.
Thanks for the reply! But this is the actually the opposite of what I'm looking for - I want to restrict the actual signature function, not use it. So I need to know how to set up the security function then? I have looked at the security section under document properties but didn't get very far.
I apologize for the delay in response to your last message.
In order to secure the document so that the signature would be restricted,You need to change the "Security Preferences" of the document through the desktop application,
You can not restrict the document features in the mobile application.
When you restrict the changes in the document, its also restrict not to use the signature function of the particular document.