nerioseole
I tried the following too: menu Tools\Preferences\Transaction tab\tick option Dynamic Fees
What other amount of fees should be used? Probably in Tools\Preferences\Transaction tab\Transactions fee per kb in unit btc / kb
I know my Electrum is outdated but this shouldn't be the reason for problem.
Electrum being outdated is the reason. The latest version fixes a bug that could cause Dynamic Fees to not work properly. You should update to the latest version which will help correct fees in the future.