To change your logo in your web form, go to Settings and select Web Forms in the sidebar.
Then click Styling. Scroll down a look if you have to mark Use Global CSS.
Then, go to Settings and select Global CSS. You will see the styles of your form and you can change it from there.
If you want to change your logo, find logo:after in the code and change the image link.
When you finish, press Save changes and Publish.
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