Issue when I upload logo pic, it messes up the whole website.

hi,

I’m looking for some help. I’ve been working on my website, when I was done putting it together, I uploaded a logo picture and it worked fin. Then I made some background changes to it and when I uploaded the edited picture the entire website would get messed up. Some one from the host company helped me once saying it had to do something with access, at that time he fixed it n i moved on. But again I did modify the logo picture and it did it again. I did a little research about any access that had to do with the header and i came accross htaccess. Has anyone had this problem and how would i fix htaccess if thats is causing an issue? Once i remove the logo picture the website works perfectly fine but when i upload it, it does the same thing or it works for a couple of hrs. I already tried changing the format to npg and a svg. Thank you

The page I need help with: [log in to see the link]