Looking to find a way to see each account that forms part of journals which has multiple lines for a specific account? i.e. looking at the prepayments detail, I want to see all the P&L side of the journals, some of these journals have multiple lines so when I look at the detail of the prepayments, the account comes through as split and for some where its a single journal, it shows the P&L account? Any ideas?

You could use a NS_CONCAT function to get all accounts in the journal in one string. Could be a start

Thanks, not sure how that would work tho? I.e. if I create a saved search and my criteria is for prepayments acc... Won't it just show me the lines against the prepayment acc and not the opposite that is part of the journal?

Here's how I would do it, run a transactions saved search based on the account to get the internal IDs of the transactions that you're looking for. Afterwards, filter down by Internal ID, and you'll have a full list of all the lines that are impacting your account here.