When investing in stocks on foreign exchange, make sure to check the currency. If the currency is different from your account's currency, the exchange rate will affect the value of your investment. For example, if you invest in USD stocks but your account currency is GBP, the exchange rate between GBP and USD will affect the value of your trade. You can find the exchange rate impact under "FX impact" in the "Your investment" section.
Note that the FOREX market and the stock exchange markets have different opening hours. As a result, any currency pair may fluctuate, and even when the market is closed, your position's result may still fluctuate based on the exchange rate.