You can customize the Thank You Message which contains a Header block and a Text block. With the help of an in-place editor, you can edit messages in both header and text blocks.
If you are using Premium Plan, it is possible to omit the SurveySparrow logo in the Thank You page.
If you wish to upgrade to Premium Plan, you can do so in the Billings page. You will find this page under Setting tab, in the Survey Builder page.