The scene is 1080x680. I understand.
But are you expecting when you preview it for the web browser window/document to expand to full screen.
This will not happen. The preview will open in the current browser window/document size, regardless of screen size.
If you browser window/document is in Fullscreen mode then the preview will display as such or at what ever size the browser is at.
Just turning scaling on for Width and Height also does not mean that your elements will automatically expand.
You need to also control them using the Metrics Inspector and it's Flexible Layout settings for each element or an element and it's content.
It probably would be a good idea to post your project if you can so we can see what you have done and maybe show the adjustments that would need to be made and if you have not already have look through the documentation on Scaling and flexible layout .