Hi @cbratschi
I believe you can try this code:
function my_acf_admin_head() {
?>
<script type="text/javascript">
(function($){
$(document).ready(function(){
$( ".-collapse" ).each(function( index ) {
$( this ).click();
});
});
})(jQuery);
</script>
<?php
}
add_action('acf/input/admin_head', 'my_acf_admin_head');
Please check this page to learn more about it: https://www.advancedcustomfields.com/resources/acfinputadmin_head/.
Thanks!