Question

How can I set the font-weight to bold in one specific cell when I select a row?

Answer 1

You can use setCell inside of onSelectRow to change the style of the cell. For example

onSelectRow: function (id) {
    var $this = $(this);
    if (id !== lastSel && typeof lastSel !== 'undefined') {
        $this.jqGrid('setCell', lastSel, 'total', '', {'font-weight': 'normal'});
    }
    $this.jqGrid('setCell', id, 'total', '', {'font-weight': 'bold'});
    lastSel = id;
}

see the demo. In the way you can set any other CSS styles.