Browsers will cache any files so it’s hard to know without more detail which files are your issue. That said, this happens most often with CSS and JS files, and WordPress is built to address this issue. wp_enqueue_style and wp_enqueue_script each have a parameter for file version (4th param in each). So long as you use these functions and up this version whenever you make a change, you should never run into caching issues with either file type.
