joseph.wasden

This is in the documentation.

Arrows
Two sets of arrows are included with the plugin. Also included is a PhotoShop .psd file that can be used as a template to create custom arrows. Be sure to back-up any modified files, as they will be overwritten when the plugin is updated. To make update-proof modifications to the arrows, place the new arrow images in the same folder as the theme’s style.css. Then, add the following to your theme’s style.css:

.collapseomatic {
background-image: url(your_down_arrow_image_here.png) !important;
}
.colomat-close {
background-image: url(iour_up_arrow_image_here.png) !important;
}

The arrow postion can be set to display right of the trigger assigning the trigclass attribute a value of arrowright. The arrow can be completely removed by assigning the the trigclass a value of noarrow. See the Trigclass Attribute section below for more information.

https://plugins.twinpictures.de/plugins/collapse-o-matic/documentation/

Perhaps this fix would help the devs?

https://stackoverflow.com/questions/6575610/jquery-accordion-collapsed-by-default-on-page-load

I actually found the solution on the FAQ of a custom post type plugin.

I receive a 404 error when viewing custom post type content
This is usually caused if the rewrite slug was changed. To fix this issue simply visit Settings > Permalinks to flush the rewrite rules in WordPress

Changing the permalink settings seems to have jogged everything back to normal.

I actually found the solution on the FAQ of a different custom post type plugin.

I receive a 404 error when viewing custom post type content
This is usually caused if the rewrite slug was changed. To fix this issue simply visit Settings > Permalinks to flush the rewrite rules in WordPress

Changing the permalink settings seems to have jogged everything back to normal.