Pasting from docs:

This option defines the toolbar of the grid. This is array with two values in which the first value enables the toolbar and the second defines the position relative to body Layer. Possible values "top" or "bottom" or "both"

$grid["toolbar"] = "top";

You can also refer code for demos / appearance / toolbar-button.php

http://www.phpgrid.org/faqs/#55
http://www.phpgrid.org/faqs/#28

what if I set on all files without declare $grid["toolbar"] = "top"; on each file

thanks

You can edit ib/inc/jqgrid_dist.php and edit this option to make default on all files.