I assume you mean ‘template owner’. The only way you cannot set the template owner is if that you have ‘use’ rights to the template, not ‘edit’ rights - but that would also mean you cannot even access the Template Settings. You previously mentioned that you created the template - are you sure or was it another user that perhaps has since been removed from the organisation? Sorry for the questions but this is really strange.
Btw, did you try to rebuild your template?