http://sparrowa7io5pz6ud3ehqzosvepbxbxt2zphmkjsylp2zgxooko23pqd.onion/docs/faq.html
When not explicitly configured using the command line argument above, Sparrow stores its mainnet config file, log file and wallets in a home folder location appropriate to the operating system. Testnet, regtest and signet configurations (along with their wallets) are stored in subfolders of Sparrow’s home folder to allow easy switching between networks.