For my site, I modified an array in modules/cms/widgets/AssetList.php to allow for a broader upload range but when I update october to the new version, the changes I made are overwritten. Is there anyway to be able to update and still save my configuration?

This behavior is normal and expected. In your case we will need a way to extend the area you wish to modify. Either by using events or configuration. Can you go in to more detail about your change?

Yes no problem. In my site I wanted to allow to upload pdf's and word documents through the backend asset browser. It threw an error saying I can only upload image files so I went in to modules/cms/widgets/AssetList.php and added the necessary extensions to the $allowedAssetTypes array. I would like this change to persist through future updates so it does not get overwritten but I cannot figure out how to extend October to do that. Thanks!