Under your shopify dashboard, navigate to "themes" under "online stores" which is under "Sales channels". Here, click on customize button for the current theme you are using. Navigate to the page, where you want to customize the banner.
Click on the story app in the sidebar.
Customization side bar appears, through which you can customize the banner to your liking.
You can change the story tile type by selecting the desired style under the dropdown under "Tile Type".
You can change corners of the banners by toggling their respective buttons under "UI Theme".
You can change the size of the banner video by dragging the bar or entering the desired percentage.
Note: after you customize the section to your requirements, please press the "Save" button on the top right side of the screen for the changes to be reflected.
