long answser, it depends on what version you are if it is an easy change or not.
if you are on the Qlik cloud version of Qlik then you can change this easily (presentation > styling > chart > axis labels)
if you are on a on prem lower version of Qlik sense (feb 2023 or lower) this is only possible if you add a custom theme to your app where you can set the bar chart text properties.
NOTE: I'm not sure if the on prem version may 2023 also have the styling capabilities of Qlik cloud. if you are on the on prem May 2023 release and if you go to presentation > styling > chart > axis labels and don't see axis labels there, then this only works in Qlik cloud for now