New bank accounts should use the default currency

[RJMurg]

Is your feature request related to a problem? Please describe.
New user to Maybe, and really enjoying transitioning over to it, but I've got a small issue bugging me.

When I add a new item to my portfolio, the default selected currency is USD, though I have my currency set to EUR in my preferences.

This has caused some cases where I add an item and set the value, but forget to change the currency, and have to delete the entire item to recreate it with the correct currency.,

Describe the solution you'd like

• Have all new items being added in portfolio to default to the currency that has been selected in the users' preferences
• Possibly allow currency conversion after creating a portfolio item, maybe asking if the user wishes to change the amount as well as the currency, or just the currency.

Additional context

[zachgoll]

@RJMurg thanks for the description here, I think this is definitely worth adding.