How to customise all emails

-- HikaShop version -- : 3.0.0
-- Joomla version -- : 3.5.6

HI,

I am struggling to customise all emails - both to clients and to admin.

I would like to drop the colour and styling and make it very simple.

For some reason editing the HTML under System > emails does not seem to update them. I am not sure also if there is a way to modify all of them at once (I only want to remove backgrounds colours, add the logo and change font colours to all emails. Everything else can remain the same as is).

Is anyone able to help me with this??

Thanks in advance!

G.