Hello @Forumboy first of all welcome to the English support forum If you are uploading images you would be better off using the tools on your editor to add your images not the attachment system as this is limited on storage space on your forum.
To add images use this button. >>
If you want more attachment space you would need to pay for a yearly package deal in your Admin page.
of course as my colleagues mentioned, prefer using the servimg image function if the attachment is an image.
For other files, or in general - if you want to set the maximum number of attachments for a post you can go to ACP > General > Messages and emails > Attachments and modify the last option of the first tab