Some visualization types use column or row headers to set axis or category labels. To set these headers, freeze cells in the first row or column. Learn more at the Visualization Index. 

1. Open your spreadsheet in Google Sheets
2. Click View 
   • Find View in the top menu bar

   • A list of options will expand 

3. Click Freeze

   • A list of freeze options will expand

4. Select the number of rows or columns you want to freeze

   • The cells will freeze: a gray line shows where the header ends

   • Repeat this step as necessary
5. To freeze cells quickly, click and drag the gray line
   • This marks the headers