Ok thank you, and in the preference options there is "Batch RBF transactions" what does it do?
Rbf is replace by fee. If a transaction has too low a few that the network can't confirm it quickly (or at all in some cases) or you need it confirming fast then you can use rbf on the tansaction(s) to speed them up.
It doesn't cost anything to enable rbf so you're better off leaving it enabled.