My understanding is that the word 'GOD' is a generic term rather like a pronoun. We know some religions have names for their gods. For instance 'Zeus'.

Am I correct in saying that the original name of god for Christians is 'Yahweh'?

If so, then why do Christians insist on using the word god as a proper noun rather than using 'yahweh'?

Yahweh is really a Jewish name for God, though the distinction between Christianity and Judaism is blurred. You'll find various terms used in Biblical translations.

Part of the use of "God" is an emphasis on monotheism within Christianity. "There is but one God", they would say. The irony is that the same Christians will promote the trinity. Go figure.

I think that "God" has practical uses in marketing. If you can equivocate everyone else's god as "God", then you can effectively steal their support. This happens, for example, with the "God of Nature" promoted by Deism, which is a very different belief than Christianity, yet Christian historical revisionists are happy to claim the "God of Nature" as referenced in some of the founding documents as the Christian god.

I agree with you that whatever the reason, it's quite annoying.

So the use of the generic 'GOD' sort of proclaims to others that this is the one and only god - no need to have a name.

Quite clever really if someone actually thought of that strategy!

Having never been indoctrinated by believers I do not understand many basic things that believers appear to take for granted. For instance when Christians say 'my lord' do they mean their god or their prophet? I am sure I have heard both. Eg 'Jesus is my lord and saviour' and ' don't take the lord's name in vain'.

"Lord" would be almost another name, one that emphasizes one's subservience.