Do open orders earn interest?
No, open orders do not earn interest since they’re removed from the borrow/lending pool and on the Serum orderbook.
How do I make a leverage trade?
Ensure the margin toggle box is checked. Simply place a buy or sell order for the asset you would like to long or short. If you do not have the deposits required for the trade and have appropriate health, the funds will be automatically borrowed. If an asset is borrowed, it is a leveraged position