Sorry to hear you are getting that error message when attempting to upload your images William, our team will do everything we can to help!
WordPress websites automatically create smaller versions of every image uploaded to them that can be displayed responsively on smaller devices like tablets and phones, and it seems that this might be the process that is failing on your website.
The information that I was able locate about this problem from other WordPress users suggests that it could be related to the PHP version running on your web server. Try switching to a different version if your hosting platform provides that option, otherwise you might need to contact your host to have them change the version for you.
Other users said that they were able to fix the problem by simply clearing their browser cache or attempting the upload with a different browser.
You could also try using the Disable “BIG Image” Threshold plugin from the WordPress repository to bypass the large image check, maybe that will help too.
Hopefully one of those solutions works for you William!