Under Settings > My company > Accounting panel, you can define your default currency.

But you can also define a specific currency for each one of your clients and suppliers.

For this, click on Edit in the Overview panel of the client/supplier in question.

All your documents for the client/supplier will then be generated using this specific currency. To know how LSP.expert manages exchange rates, see this article: https://help.lsp.expert/en/articles/747032-how-are-the-exchange-rates-managed-in-lsp-expert-and-can-i-edit-an-exchange-rate).

In the reports, you will see one line for each currency you defined.

You can also filter the reports on one currency in particular (Filter button in the report) and you can tick a box to convert all the amounts in the reports into your default currency (click on Filter in the report in question and scroll down to the bottom of the popup that opens). For the amounts already paid, the system will use the exchange rate that was applicable at the payment date. For the amounts that are not paid yet, the system will use the last available exchange rate.

In your settings (Settings > Accounting), you can define your default currency...

...But you can also define a specific currency for each one of your clients in the Clients tab.

All your documents for this client will be generated in this specific currency.

In the reports, there is one line for each currency you defined.

You can also filter the reports on one currency in particular and you can tick a box to convert all the amounts in the reports into your default currency. For the amounts already paid, the system will use the exchange rate that was applicable at the payment date. For the amounts that are not paid yet, the system will use the last available exchange rate.