Sifency Bulk Metadata Commander lets you update many posts at once instead of editing them one by one.
Bulk update, in a guided step-by-step tool
Media Usage — find and replace media across your site
On its own admin screen, pick any file from the Media Library and instantly see every post (of a chosen post type) that uses it — as a single custom field, inside an image gallery, or as the Featured Image. Check exactly the usages you want to update, choose a replacement file, and Sifency Bulk Metadata Commander swaps it in only for the posts you selected — everything else is left untouched.