Yes, default templates can be personalized to your liking but must be converted into a personal template first. You can edit and save templates as a new template that is only visible to you.
To convert and customize templates, go to Settings > Marketing Management > Templates and select the template(s) you would like to customize, and click convert.
You will find both the default templates and your personal templates on this page. To edit a template, click on the template name and you will be redirected to the template editing window. From here, you will be able to personalize the text, add merge fields, and add tags to the template. There is also a preview window where you will be able to see how the template will appear when sent to a contact.
Please note we use Alex Stapleton as the test contact for all merge field information.