You can set a border radius for buttons in the Design settings, which will apply to all buttons in the email/survey, or you can select an individual button and style it separately.
To Set Border Radius for All Buttons
- Go to Design in the right column.
- Click at the Buttons tab.
- Scroll down to Border Radius and adjust the slider.
To Set Border Radius for an Individual Button
- Select the button and click on the Design tab in the right column.
- Adjust the Border Radius slider.