The logo doesn't show up on my site when I'm adding one..

1. Regarding the issue about uploading logo image.
I think that the issue is caused by selecting wrong chmod setting (permission setting) for the upload folder when uploading an image.
To fix this issue, you need to reset the chmod for the folder to 755 by :
– Use your FTP account
– Right click to your image folder ((public_html > wp-content >  uploads ) select file permissions
– Change the Numberic value to 755, see below screenshot:

If you still face the same issue, please send me username & password of your site (via private answer). I will help you resolve your issues.
Hope this helps !