Mantis Bug Tracker - Forums

Is there any way to set 'show complete bug info' option from 'view issue' section as default on 'ON' value. So user don't has to click every time after opening bug into this button when he wants to see more bug details. Thanks in advance for your help.

I don't understand what you mean.
I am not aware that there is an option show "complete bug info" on any page of MantisBT.
Maybe you can attach a screenshot.