Hello @koni1978,
For this issue go to WordPress Admin Panel -> Plugins -> Plugin File Editor -> Select plugin to edit: choose Responsive Accordion And Collapse then click on select -> front -> ac-content.php
then at line no 80 you will get this code
<a class="<?php if($i!=1){ echo "collapsed"; } ?>" data-toggle="collapse" data-parent="<?php if($enable_toggle=="no") { ?>#wpsm_accordion_<?php echo esc_attr($post_id); ?> <?php } ?>" href="javascript:void(0)" data-target="#ac_<?php echo esc_attr($post_id); ?>_collapse<?php echo esc_attr($i); ?>" onclick="do_resize()">
replace with this
<a class="<?php if($i!=1){ echo "collapsed"; } ?>" data-toggle="collapse" data-parent="<?php if($enable_toggle=="no") { ?>#wpsm_accordion_<?php echo esc_attr($post_id); ?> <?php } ?>" href="#ac_<?php echo esc_attr($post_id); ?>_collapse<?php echo esc_attr($i); ?>" onclick="do_resize()">
then click on update file button.
Let me know if any issue.
Thanks