Very important, any share you have sent out can be modified after you have sent the mail out, so no worries that you accidentally gave a receiver the option to download the original master file ot the link expired, just go to the“User options” menu and here you can modify all permissions. And you do not need to re-sent the link, just ask the receivers so refresh the browser where the link is.
Click on the arrow to open the User options menu
Here you can see what options is enable and how many logins there have been. So if I was to enable the master download and extent the expire date then I just can do that.