We need to know your Squarespace version. Here's how to find out:

1. Log in to your Squarespace account.

2. In the left-hand sidebar, look for a "Help" or "?" icon.

3. Click it, and a pop-up should appear. The Squarespace version will be displayed there (e.g., Version 7.0 or Version 7.1).

Once you know your version, follow the appropriate steps below:

Version 7.1

1. Edit Mode: Click "Edit" in the top-left corner of your site preview.

2. Header: Hover over your header and click "Edit Site Header."

3. Site Title: Click on your site title or logo, then click the pencil icon.

4. Styling Panel: The styling options will now appear. Look for "Font Size" and adjust accordingly.

5. Save: Click "Save."

Version 7.0

1. Design Panel: Go to "Design" and then "Logo & Title."

2. Site Title: Click on the site title area to open editing options.

3. Site Styles: Open Site Styles and select "Fonts."

4. Assign Styles: Click on "Assign Styles" and find the "Site Title" section.

5. Adjust Size: Change the font size using the provided options.

6. Save: Click "Save."