Let's Call the Whole Thing Off

So there's American and there's English and then there's Scouse! I haven't got a particularly strong accent so why do some people find it difficult to understand me? Ok so my well travelled friend who is British Caribbean (how are you going to pronounce that?!) speaks so well he probably makes me sound as common as muck but I do change my accent out here, I mean it's my job after all! Mostly I get it. If I want to order frozen yogurt I can't say yogit (Scouse) or even yogert (Standard English) as it is a different word and I'm all for 'When in Rome'. Butter is another one. It needs to be budder (I can't even type the Scouse equivalent!) But water? Water? Dear American friends, I'm in a bar or restaurant and I'm asking for water what else can it be??? Oh and just for the record no one can understand the posh island dweller when he orders that either!