If my logo appears with a solid black background. Does anyone know how to remove the background?

You can manually edit the logo outside QuickBooks Online (QBO), @dyan2. We'll provide more details to help you upload your preferred logo to the program.

When uploading a logo via the Account and settings or through sales forms in QBO, the option to adjust its dimensions and other aspects isn’t available. To remove the solid black background or change its appearance, manually edit the logo outside the program before uploading.

After removing the solid black background, you can save the image as a PNG file. This way, when uploaded into your company file or in your sales forms, your logo’s design is highlighted properly with no background added.

On top of that, if you want to adjust the logo's size, you can visit this page for more details: Add, customise, or remove logos on sales forms.

Please let us know in the comment section if you have any additional questions about the program or need assistance performing specific tasks.