Changing default handling time, help please

Hi All

Can someone please clarify the following. I have my books set at a 5 day handling time & my maps at a 2 day handling time. I want to change all my listings books & maps to 5 days for a small period of time.

I have seen videos which talk about downloading active listings & editing them & then re-uploading that’s a bit over my head. Now I have seen something about changing the default handling time in seller central within the shipping settings page.

This might be daft question as I type it out but can anyone confirm if I change the default to 5 days that it will apply that to all of my active listings?

Thanks in advance.

Ed