The new electrum 4 is very different from the previous. The interface has changed and the features as well. This version infact supports also lightning network channels and transactions. The procedure of sending onchain transactions has changed so much and here we want to see how to do that using electrum on the testnet.
First of all go into the coins tab of the wallet, then choose a UTXO you want to spend, right click > spend. The utxo is lighted by green and shown on the bottom.
Then go into the spend tab, you will still see on bottom the hightlighted green line containing what you are going to spend. Write the destination address. Now click on pay.
When the popup is shown, just click on advanced in order to check transaction details and preview.
Here you can see the inputs and outputs of your draft transaction. You can also choose if using RBF (replace by fee) and the target miner fee. When all is ok, click on finalize.
Then just click on sign, in order to make signature. If using an external device you will have to confirm on it.
When signature is completed, all is done, you just have to broadcast the transaction, clicking on the button with same name.
The transaction is then broadcasted to the network, you just have to wait the first confirmation come.