Bug: Investment transaction in USD only

[Aohzan]

Describe the bug
When I want to add a transaction, I can't change the currency, it's forced to USD despite EUR is set in my settings. So when I add a transaction there is a mismatch between the current value from Synth, in the following example I bought à 149.15€ and now it's 165, but

To Reproduce

1. Set EUR on global currency
2. Add a buy for a european stock (Euronext) and put the price in EUR

Expected behavior
Choose the currency of the transaction and/or account must used the global currency

Thank you

[zachgoll]

This will be covered in #1087