you should always use the historial rate for capital and any difference in closing rate (the exchange rate at year end date) should go to Exchange Reserve, an equity account (balance sheet item)
All balance sheet items should be recorded at closing rate including assets, liabilities while equity account items usually recorded in historial rate as mentioned above.
If this is the first year that the capital is recorded in another currency, you should use this year's rate to record capital.
ALL items in Balance sheet should be converted into the new currency including fixed assets and depreciation, thus an exchange difference may be arise.
Fixed asset should be recorded at "closing rate" (the spot rate of period end), any exchange difference should go to equity as exchange reserve until disposal of assets.
Depreciation should be recorded with "average rate" (the rate for recording P&L items) as it is an expense item, exchange difference should go to P&L as well.
"什麼都不做都可以" solely because of the amount of these items are immaterial in view of auditor, who only focus on material and significant items, doesn't mean these items are free to adjust in the case of change of currency!!!
just a reminder, if your company is a limited company, your auditor has to issue a financial report and the capital in B/S has to be changed to reflect its true and fair value eventually.