The html is coded in the admin files. There is no direct setting to say show more. The field input boxes I think display like 30 characters there is no maximum so you can input the actual data that needs to be there. There is no need to show it all as that would mess up some peoples displays which is why it is not wider for compatibility with everyone as our app has to be.
Content visible to verified customers only.
The 30 is right on line 2999-3000 of adm-misc.php file you can change that to say 50 if you want there