Hi Kim_Boehm ,
You can achieve this using JS, first create the BackButton_cnt embedded variable at the start in survey flow and add the below JS code in Look & Feel -> General -> Header -> Source.
In the BackButton_cnt variable the count will get stored every time you hit the back button.

Hi SurajK,
thanks a lot for your super fast reply. I am not expert but this code counts the clicks on any back button in the survey, right?
So, if I have a back button on page 5 and page 10. On all other pages (1-4, 6-9, 11-15) I hide the back button.
Can I achieve the same with two variables counting the use of "back button 1" (page 5) and "back button 2" (page 10) seperately? More precisely, I am interesed in whether back button 1 is used more or less than back button 2. However, both buttons are just the " '.PreviousButton' " that is standard in Qualtrics and hided on some of the pages.
Thanks again,
Kim

Ok, so you are looking to count the backbutton click for the specific question, then you can simply create the 2 embedded variables as you mentioned above and use the above code at question level.
For page 5 use the below code,
Qualtrics.SurveyEngine.addOnReady(function()
{
jQuery('.PreviousButton').click(function(){
var currcnt1 = Qualtrics.SurveyEngine.getEmbeddedData("BackButton_cnt1")
currcnt1=Number(currcnt1) + 1
Qualtrics.SurveyEngine.setEmbeddedData("BackButton_cnt1",currcnt1)
});
});
And on page 10 use the below code,
Qualtrics.SurveyEngine.addOnReady(function()
{
jQuery('.PreviousButton').click(function(){
var currcnt2 = Qualtrics.SurveyEngine.getEmbeddedData("BackButton_cnt2")
currcnt2=Number(currcnt2) + 1
Qualtrics.SurveyEngine.setEmbeddedData("BackButton_cnt2",currcnt2)
});
});

Hi SurajK,
thanks a lot for your answer and effort! That is exactly what I searched for and it works perfectly!
Cheers,
Kim