I have no idea if it was asked before. when spending from paper wallet, we need to create a watch-only wallet first, then electrum gets some data from bitcoin network and save it into a file, then we sign that file with the real-wallet.

so basically while seeing the bitcoinjs documents, to create a transaction we need a "TXID" of a pervious transaction. so if if have a wallet with multiple transactions and all of them are deposits, then which one do we need its TXID now? can anybody please explain?

also, why do we need a watch only wallet first before signing transaction? i mean what kind of data does electrum get from the address and the network.

tnx in advance