Change header based on location in survey

Hi Qualtrics community, Has anyone had to change the header based on where the respondent currently is in the survey? The respondent must be able to back up, so I'm unable to use Survey Flow logic to change the header. I'm aware that there is an OnPageSubmit, but is there an OnPage 'Previous button' function? Maybe I could change an embedded data variable's content when they click previous vs. clicking next? Pete