Acrobat X is not a compatible version with Mac El Captain,i.e 10.11.
This is why you are experiencing issues with Acrobat X.
Err, who says? and why is that?
May I say that I find this totally disgusting?
It is not a question of upgrading to get new features, it is a question of being forced to pay over GBP200 simply for the software to keep working.
This behaviour is worthy of Microsoft circa 1990, i.e. a monopolist squeezing its customers and treating them with contempt.
Kindly pass this on. I thank you for your help but I do not wish the company well.