Tracking Transactions in a Foreign USD Brokerage Account

I'm seeking guidance on tracking transactions in a foreign brokerage account where the base currency is USD, especially in regards to the remittance basis of taxation. 1) For the purpose of tracking all transactions (buying and selling futures contracts), should these transactions also be tracked in GBP (besides the original USD) at each transaction level, or is it enough to track them at the point when remitting to the UK? 2) If transaction level tracking has to be in GBP; when remitting amounts, the exchange rate when USD was extracted (=£10,000) from the brokerage acount, could be different at the actual time of exchange to GBP when reaching UK (Example: £9,500). -Which amount should be noted as removed when tracking the remains in the brokerage acount? -Which amount should be recorded as remitted to the UK? 3) If some years are arising basis and others are remittance basis, should there be any changes in regards to tracking? Thank you

Hi,

1. It can be at the time of remitting.   
2. It will be the amount at the time the mony is removed from the account.    
3. No.

Thank you.