why does the exchange rate field missing, when entering a foreign currency transaction?

Hello, @c-lim. The technical issues affecting QuickBooks Online, such as the missing exchange rate field, are often caused by browser cache.
 

To address this, and for you to be able to use the exchange rate field successfully, let's refresh your page and log out of your account, then log back in. This can help establish a fresh connection to the system and may resolve any temporary issues.
 

Please let us know if you need any further assistance.