the question is; how to press CTRL with the "+" in the laptop so to increase the letters size

in many editors we can increase the fonts size by pressing CTRL and "+" and to decrease we press CTRL and "-"
this is in thinbasic editor and in notepad++ and others
but this is when i use the Desktop computer in which there is a big "+" and "-" on the rightmost of the keyboard
i got an old laptop hp pavilion ze000 from year 2006. i can't do the same with the laptop. i have asked someone have modern laptop and he said CTRL with "=" works to increase the fonts size. but it does not work for me.
any ideas. Thanks