Offline Transaction Signing

It is a better security measure to store your wallets in an offline device that is air-gapped, to mitigate risks of your wallet keys getting stolen. For example, you can disconnect all network connections, bluetooth, wi-fi etc. in a new laptop and store your wallets in the air-gapped device. When you need to execute a transaction from a wallet stored in such a device, instead of connecting the laptop to a network, you can instead use the offline transaction signing feature described below.

Ensure you have the latest version of the desktop wallet installed. You may either download this wallet once and disconnect the laptop from all networks or copy over the wallet from another device in a USB drive. It is best to use a new USB drive and ensure you scan the drive using an antivirus software.
Open the desktop wallet app in the disconnected device and create or import your wallets.
Under the settings option down on right bottom side of the app, select the option that says 'Offline Transaction Signing'.
Select 'Enable' and then 'Ok'
Next time you want to send a transaction, just use click send button. Other transactions types such as conversions also will display similar pattern described below.
Among other fields prompting your input, you will also see a field named the 'nonce'. If this is the first transaction that is being sent from the wallet, you can leave the default value as is. If you had sent other transactions from this address before (including conversions), you will have to note down the nonce from QuantumScan block explorer on another connected device. To do this, paste the address in the connected device and search for it in QuantumScan. You can also get the address to search from your wallet screen's QR code option for the wallet.

Note that if QuantumScan shows that your address is not found, then it is likely there were no transactions sent from it yet, in which case you can leave the nonce to it's default value.
Enter the nonce value in the input box for the nonce in the disconnected device in the send interface.
Fill rest of the fields for sending the transaction. Click on send and continue the steps in the wallet app. In the final stage of the send process, you will be shown the signed transaction data.
Copy the signed transaction data into a USB drive and bring it to another computer that is connected to the internet. In the future, you will be able to do this using a QR code, but QR code support is not available at the moment.
In the computer that is connected to the internet, open this current webpage: https://QuantumCoin.org/offline-transaction-signing.html.
Paste the signed transaction data into the following textbox and then press 'Submit Transaction'.
If the submission was successful, you can monitor the status of the transaction in QuantumScan for your address. Note that it can take many seconds to minutes for the transaction to show up in QuantumScan.