zPIV by nature, will convert 10% of your balance to zPIV. You can read more about zPIV here
To prevent the wallet from automatically converting follow the following steps. (or check out the video guide here)
1.Click the "Tools" tab from the top menu bar.
2. Select the "Open Wallet Configuration File" option. (Also can be accessed via the data directory- see more here)
3. Add this to the config file: enablezeromint=0
Then, restart your wallet, and you're wallet will stop auto-minting zPIV. Enjoy!