I am trying hard to help the user, but he is not being very helpful in providing screen shots and diagnostic info.
He has posted a screen shot of the output from:
//echo -ac Normal width $window(-1).w height $window(-1).h / dbuw $dbuw dbuh $dbuh
and it is:
width 2560 height 1920 / dbuw 2.5 dbuh 2.5
By comparison, on my laptop the results are:
width 1920 height 1080 / dbuw 2 dbuh 2
So the values for dbuw/dbuh look OK.
Here is what they look like: