Filtering default options

I’m just setting up the plugin for the first time, and am having some problems setting the plugin defaults. As a starting point, I’ve copied and pasted your example set_accordion_shortcode_defaults code into functions.php, but it seems to have no effect. Starting a new accordion still leaves Open First unchecked, despite being included in the filter as true.

Sorry there’s no error code to report here, but are there any suggestions to get this working?

Also, once I’ve got that first option working, should defaults for additional defaults be their own entries (ie, $atts[‘openfirst’] = true; $atts[‘scroll’] = true;) or should they somehow be combined in a single array ($atts[‘openfirst’,’scroll’] = true;)?

Thanks!