HTTPS error on logo

I have moved my page to https and I’ve changed all the internal links on the front page to link to https. However the logo image still links to http causing the page to show as “mixed” regarding security. How can I change this? If I just delete the logo image and the “Zerif Lite” image shows up everything works fine. I have tried several images, but the same error occure.

Thanks for your help

/Peter
https://vibblaby.se