I had a similar problem with this widget on this extension. I wanted to use the field for a Birthday field, but the extension is set to display by default the today date, without letting the user change the year directly.
I realized that the widget used is Jquery (google it)
So, I modified this code to add year modification options in UWjuidate class on ./modules/user/components/UWjuidate.php line 61, as follows:
$options['dateFormat'] = 'yy-mm-dd';
$options['changeMonth'] = true; //added by me to support month changing
$options['changeYear'] = true; //added by me to support year changing