How do I make the expand ([-]) and collapse ([-]) buttons of a pivot table larger?

[#1]

Can you please help by providing an example or explaining how I can make the buttons in a pivot table which expand and collapse dimensions larger? The screenshot below has a red arrow pointing to the button in question -

I would like to either be able to make the expand and collapse buttons bigger or can I change them to different icons?

[#2]

I have the same problem when users see the apps by web, but not find any way to solve this.

Regards.-