Here you can see how I have sent the 6.4 to my new address at 00.30. But the address with 6.4 on it I do not have at Electrum. Do not look right now. Can anyone explain to me?
It's called a "change address". To make it simple, whenever you make a transaction, the remaining funds will be sent to a change address, instead of returning to the originated address.
You can disable this feature by doing the following steps:
Tools > Preferences > Transactions > Remove the tick on "Use change addresses".
But I do not understand it. so is the blockchain more burdened?