Change display date format in widget (month-day-year)

In the wiki there are some instructions for customizing this.

Let’s say you want “month-day-year” as in 11/06/2017.

Here’s how to this can be expressed using the shortcodes of the PHP “date” function, documented at php.net

m = Numeric representation of a month, with leading zeros
d = Day of the month, 2 digits with leading zeros
Y = A full numeric representation of a year, 4 digits

So this would get the expected result:

function my_custom_filter_example( $mem_date, $mem_event_list ) {
    
    return date_i18n('m/d/Y', $mem_event_list["start-unix"]);
    
}
add_filter( 'mem_event_date_display', 'my_custom_filter_example', 10, 2 );

Caveats:
This code is only considering the start date, not the end date.

How to add this custom PHP code to your site?
Here’s a tutorial that may help.