Problem solved.
The transaction has magically disappeared from the list.
If I had first reported the problem I would not have expected so much.
However, I would like to understand how to set Electrum correctly and not find myself again with the same problem.
Thanks however for your attention.
Gio.Co
First upgrade to the latest version of electrum, then use the instructions in this quote to set dynamic fees on your wallet. Afterwards your wallet will automatically work out the best fee to pay by itself, and adapt its fees to account for increases or decreases in the number of unconfirmed transactions in the network.
For future transactions try these instructions, they are for the latest version of electrum. Older versions have a different layout for the settings windows.
Click tools in your menu bar, then preferences in the drop down menu that appears.
Click the fees tab in the window that opens and copy the settings from this screenshot. Click the close button to close the preferences window
When you send coins move the fee slider shown in this screenshot all the way to the right for fast confirmations.