Reminder: if you’re only making US-domiciled purchases on IBKR, then it makes far more sense to have your base currency set to USD and then simply convert the entirety of your CHF deposits to USD each time. This way you only have one currency with which your purchases and monthly fees are deducted from.
I feel that a lot of people are complicating things by setting their base currency to CHF (perhaps because this is what a lot of Swiss-based bloggers like thepoorswiss are writing in their tutorials).
@Bojack, I’m pretty sure this was originally advice you had written back in like 2017, so thank you for that!