Showit utilizes an autosave feature that saves after every change you make. You can see the process happen in the Showit builder by looking to the left of the Preview and Publish buttons. You will see three dots processing while changes are saving:
Then once the changes have saved the dots will display the saved message:
Then you are all set! It is important to note that saving changes does not mean those changes will be published to your live site. You will always want to click publish after making changes you wish to be displayed on the live site.