I am having this issue with picture box, where it have to load images for categories from the web, the problem is when the image is changed on the server, it still load the cached copy.
PictureBox class uses a
WebClient instance to load the image from the server as you can see in the always usefule source reference from Microsoft.
WebClient.CachePolicy property is not explicitly set (which is not done in PictureBox.Load) then
WebRequest.DefaultCachePolicy is used.
So depending on your application you can choose one of these approaches:
PictureBox.ImageLocation. This is explained in How to clear the cache of HttpWebRequest
Download the image with your own WebClient instance with set CachePolicy and initialize the PictureBox from the downloaded content stream like Load Picturebox Image From Memory?
WebRequest.DefaultCachePolicy globally (as a last resort) e.g.
WebRequest.DefaultCachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);
Hope this was helpful.