Smartphone: Battery should also be displayed in percent

I have a Samsung phone with Android. A friend of mine also has the same phone, but at her phone, the battery indicator above in the status bar is displayed with percentages. At my phone, however, the status of the battery is only symbolically displayed without the percentages.

I would also like to see the figures in percent, because so you can estimate much better, when the battery will be empty and when to recharge.

I asked her how she did that, but she did not remember. Does anybody know that? I know that somehow it has to work, because after all, she has the same smartphone and she has this function!