If you set a default value of a global variable in a template and then create an email from it - if you then go in and change that default value in the template and re approve it - none of the emails that run off that template update..
The old email will still have the previous default value, even after re-approval.
Is that intended?
yes it is. Default values are only used when you add the module (for local variables) to the email or create a new email (for global and local variables). After this, the email being created, the default value becomes the email value.
I'd like to add, module styling does not update if you change the template styling, even if it is a fixed value and not using variables.
Marketo appear to have made no link between modules, once a style is set in the template, that module styling will not be updated if you edit that template.
Is this a mistake by Marketo? It seems to make very little sense.