Can I change the expiration dates to be the same ?
It is not possible to sync the expiration dates of your domain names so that they all fall on the same date. This is because registration periods and renewal requirements vary by extension.
What you can usually do, however, is to simply renew all of them on the same day; as long as the renewal date that you choose is before the closest expiration date of one of the domains, then you are sure to renew them.
Another possibility is to set up automatic renewal for your domain names. When you do this, they will be renewed in turn, drawing on funds that you would have added to your prepaid account.