SSL and Mixed Content

Hi. I want migrate my site from http to https, and I’m trying to fix some issue with mixed content.

I resolved almost all, but I’m not able to change the path of the small thumb within the widget latest post (attachment-small-thumb size-small-thumb wp-post-image).

For example, I want to change from

http://mysite/wp-content/uploads/myimage-60×60.jpg

to

https://mysite/wp-content/uploads/myimage-60×60.jpg.

I would like (if possible) to change it in Aqua theme, not in the database…

Please, may you heplp me?
Thank you.