The answer to 'how to fix faucet installation' is to first turn off the water supply to the faucet, either at the shutoff valves under the sink or at the main water supply. Then, remove the old faucet by unscrewing the mounting nuts or bolts that hold it in place. Clean the sink surface and install the new faucet according to the manufacturer's instructions, making sure all connections are tight. Finally, turn the water back on and check for any leaks, adjusting the faucet as needed.
Proper faucet installation is important to prevent leaks and ensure the faucet functions properly. If you are not comfortable performing this task or encounter any issues, it's best to call a professional plumber to ensure the job is done correctly.