Hi,
Editing a magento template using TT 5.0.0.6906
If you remove "designed by" in desktop it disables the ability to remove "designed by" in tablet and mobile view.
but if you to remove it from mobile and tablet you have to disable it from mobile/tablet views first and then remove desktop.
It's an annoyance and there shouldn't be a restriction on removing "designed by" if it's already removed in desktop view.