How do I get a new key. I have had to switch computers.

Please note that if you lost the original key, the already received data will not be decrypted.

So, please disable the feature, and if you still want to use encrypted forms, enable it again to generate a new encryption key to decrypt the new data you will receive.

https://www.jotform.com/help/344-Encrypted-Forms-and-How-to-Use-Them