You can add the logo to your theme(if add logo feature is avialble in your purchased theme)
Here we know how to add online logo to your theme.
We are using the theme name 'onlineeducation') at below image, In your case, your theme name would be applied instead of 'onlineeducation'
After put these values please save your settings by clicking on save button at bottom of the settng page .
At last don't forget to do 'Purge All Cache' by
Home ▶ Site administration ▶ Development ▶ Purge all caches