Thanks for reaching out about this, Trevor6. Here's what's happening with that error message.
The Exchange Gain Loss account is created automatically by QuickBooks when multi-currency is enabled and locks it for editing. This system restriction is why you're encountering an error when trying to change it to Other Income.
QuickBooks uses the "Other Expense" category to track both gains (negative) and losses (positive) in a single account. Preserving this setup is critical for maintaining calculation accuracy.
Feel free to visit this article for further guidance and information: Manage default and special accounts in your QuickBooks Online chart of accounts.
The Community is always here if you need anything else.
