Nintendo Switch - password protect specific titles?

You can use the Parental Controls feature of the Nintendo Switch.

Parental Controls can be controlled on the Nintendo Switch itself, or via an app. Here's a table of what can be controlled with which:

Using Parental Control will also lock the entire console with a PIN:

Please note that the Parental Control PIN will automatically be required when initializing the system and when adjusting some of the System Settings (date/time changes, deleting a user, etc.).

Nintendo Support has an article detailing how to enable Parental Control.

Since you mentioned the existence of older siblings:

• Parental controls are set for the system, not each individual user. The same restrictions will apply to everyone who uses the system, so they should be set with the youngest player in mind.

So if any of the older siblings want to play a game the toddler doesn't have access to, they'll have to ask you for the PIN to unlock the game. Make sure they don't find out your PIN.

To set up Parental Control on the Switch for the first time:

1. Select System Settings on the HOME Menu.

2. Scroll down to highlight Parental Controls, then select Parental Controls Settings.

3. Select Use this Console.

4. Select Restriction Level.

5. Choose from preset restrictions by age or select Custom Settings to manually adjust the settings. Select each setting that you want to adjust:
   
   Important: Nintendo eShop restrictions, including restriction of spending/purchases, must be set in the Nintendo Account settings.

   • Restricted Software
     Restrict software by age based on each game’s ESRB rating category. Select Restricted software, then choose the age you would like to restrict software for (6+, 13+, etc). Additionally, videos captured using restricted software will not be viewable in the album.

   • Software Rating Organization
     Adjust the software rating organization that software restrictions are based on (ESRB, PEGI, etc). This defaults to the appropriate organization for your region.

   • Posting Screenshots/Videos to Social Media
     Disable the ability to share images and videos from Nintendo Switch on social media. Toggle between Restricted or Not Restricted.

   • Communicating with Others
     Restrict open communication between users, including chat features and exchanging messages. You can toggle between Restricted or Not Restricted for all software on the system, or adjust the settings for specific software.

   • VR Mode (3D Visuals) Restrict gameplay in VR mode. This option should be set to restricted if a child of 6 years or younger uses the console. Toggle between Restricted or Not Restricted.

6. Once the restrictions are set as you want them, select Save, then select OK to confirm.

7. Choose a PIN number (between 4 and 8 digits long), then select OK.

   • If you use the Control Stick Input (default), each direction of the Control Stick is a number (1 – 8), the Y Button is 9, and the X Button is 0.

   • If you would prefer to enter the PIN using a number pad, hold the (+) Button (Keypad Input) then use the onscreen number pad to enter your PIN.

   • If there are children in the room that you don’t want to see the PIN, you can either undock the Nintendo Switch and enter the PIN in handheld mode or use the Control Stick Input.

8. Re-enter the PIN to confirm, then select OK.

   • If you are having issues with the PIN confirmation, try using the Keypad Input to enter the PIN and/or select Show when entering it to display it on the screen. (Note that this will be visible to anyone in the room if you enter it while in TV Mode.)

Remember that kids can be very persistent and might try to brute-force your PIN, so I recommend using an 8-digit PIN. If you have reason to believe they somehow found out your PIN, don't hesitate to change it.