Hi Beth, ultimately the rule is that ownership stays with you until the buyer approves/purchases the content. So if your initial job from the New Clients board is cancelled, you own the content — but if you submit the same content in a longer job later, the buyer owns it after approval. Only if you rewrote the topic from scratch would you still own the content from the shorter initial job that was cancelled.
Note - the word count cannot be increased beyond 250 for those initial jobs, so the client has to assign you a separate job if they want you to expand the content. So the client can 1) pay for the initial job and assign another job or 2) add you to favorites but not purchase it, and assign another job, in which case the initial piece will continue to appear in your Cancelled folder.