dear as we faced a devaluation of our currency versus USD, we used to register all transactions in USD as the transaction rate from the USD to Lebanese pound ( 1$ = 1500 LBP)
versus the nonstability in currency rate vs USD, I need to convert all the USD transactions done in the past to LBP, in the cash account, invoices, expenses, payslip by multiplying all these amounts by the old rate 1500 and then I will continue to invoice in the local currency
kindly advise how can I do this
I believe you should not do this. Prior transactions entered in Manager record what happened at the time. You cannot arbitrarily convert them to what is, effectively, a new currency. You should probably create an entirely new business, defining a new base currency. Set starting balances in the new currency and move ahead from there.
This is a change of such magnitude you should not begin the process until you have consulted a qualified local accountant who understands the legal consequences of the devaluation.