Oh, Thank you. It should be explained on the Kraken web because I have spent a long time looking for the solution (I should have asked before... ;-) )If it is, I did not find it...

How do I trade using leverage?

Selecting a leverage option is as easy as toggling a button when ordering. The leverage options are only available on the Intermediate and Advanced order forms. Please see our Trading Guide for in depth instructions on using leverage and margin. Note that leverage is currently disabled.