The Book Bolt Studio is made with all browsers in mind, however there can be small issues at various time with browsers that are not Chrome and a persons computer configuration.
Our best advice is to switch to Chrome and try it and see if it has the same issues you had in Safari or another browser you were using.
If you do not have Chrome, then please download it from here.
If this does not help your issue then please click help from the drop down menu in the studio and click "Submit a Help Ticket"