Multi-currency for payments, moves, etc

Hello team,
I have an issue understanding multi-currency account in order to create a journal entry. My local currency is CRC. I understand I need to select the checkbox to make the entry multi-currency, but let’s assume the following scenario: Customer transfer $100 to pay a debt, the account that will impact those $100 it’s in CRC; the issue is that I want to be able to enter $100 as the amount “paid” to the account in CRC and the system should be able to convert that, but when I type in 100, it converts it 100 CRC, not $100. Am I right on this, or what is the behavior for such scenario? Thank you.

Thank you for your response, but the documentation does not seem to have the details I’m looking for, or I don’t understand. I want to know how the multi-currency in the system address a situation where I want to add $100 to an account that is CRC currency. The system should be able to accept my $100 entry and convert it to my local exchange, isn’t? If so, how I indicate that I’m entering $100 instead of 100 CRC. Thank you and I hope this makes sense.