Add custom logo to a form

I'm having issues uploading a custom logo for my forms.  There does not appear to be any help topics in your User Guide for this.  What file formats can I use/not use?  What should happen after I upload a logo (currently, nothing happens after uploading a .TIFF file).  It does not seem to accept .pdf files.

To add custom logo to your form kindly check out the demo below on how to do so. Kindly not that to add logo most common image formats are supported. Unfortunately PDF and TIFF image formats cannot be used as logos.