Problems with removing an old favicon

Hello, since one week im trying to remove an old favicon from my site. I´ve changed my complette site from http to https. That´s all o.k., but the old favicon is still called with the http. Thereby the browser got no "green lock". I´ve changed all references for the favicon from http to https in the php files. In the Datebase i´ve also changed it in wp_options -> _transient_fullframe_favicon. With this changes i´ve got my green key. But on the next day this database entry has been changed back to the http. Now I´ve watched there else the favicon is called with the http. I think there is an autoload wich overwrittes the _transient_fullframe_favicon entry. I´m running fullframe Pro with an Child Theme called "Design" Now I´ve changed the http...favicon.png to https...favicon.png in wp_options ->theme_mods_Design. The result is that Wordpress won´t access to the fullframe theme. Now my Question is: Where have i to do the changes, that the favicon will be durable called up with the https entry? Sorry for my bad english. I hope anybody understod my probleme. Thx a lot Tobi