you can disable the autofill feature by adding a site to the list of Ignored web addresses (Settings - Ignored web addresses). Then you won´t be asked if you would like to add an account for the selected site.
You can disable also only the auto sign-in feature in Edit account dialog - "Links" tab - "Automatically activate account after loading" option.
The "remember me" checkbox can be also autofilled by editing the account using the Manual Form Edit feature (Edit account dialog - Manual Form Edit tab). But it´s not necessary to set the site to remember your login because if you create an account for the site in Sticky Password, your login and password for this site will be securely saved in the database and then automatically filled by Sticky Password.