Controlling your child's computer time can be a challenging task, but there are several steps you can take to help manage their screen time:

1. Set clear boundaries: It's important to have a conversation with your child about how much time they are allowed to spend on the computer each day. Be specific about when they can use the computer and for how long.

2. Create a schedule: Work with your child to create a schedule for when they can use the computer. This can help them manage their time more effectively and ensure they are not spending too much time on the computer.

3. Use parental controls: Most devices come with built-in parental controls that allow you to set limits on your child's screen time. You can also use third-party apps to block certain websites or apps.

4. Encourage other activities: Encourage your child to engage in other activities such as reading, playing outdoors, or doing arts and crafts. This can help them develop a healthy balance between screen time and other activities.

5. Lead by example: Finally, it's important to lead by example. If you want your child to spend less time on the computer, make sure you are also limiting your own screen time and engaging in other activities.