My Mac air is scrolling freely thru the screen after you release the key . Have replaced the key pad . Any ideas please ? thanks

Hi torana1977,

We appreciate you reaching out to us.

We’d like to gather additional details that may help us be in a better position to assist you.

1. Are you experiencing the issue on multiple apps?
2. Have you made sure that there no keyboard keys that are stuck?
3. Have you disconnected any accessories that may cause the issue

If you answer yes to all questions, let’s test if the issue persists on a newly created user account. 

1. "On your Mac, choose Apple menu > System Settings, then click Users & Groups  in the sidebar. (You may need to scroll down.)
2. Click the Add Account button below the list of users on the right (you may be asked to enter your password.)
3. Click the New Account pop-up menu, then choose a type of user.
4. Enter a full name for the new user. An account name is generated automatically. To use a different account name, enter it now—you can’t change it later.
5. Enter a password for the user, then enter it again to verify. Enter a password hint to help the user remember their password.
6. Click Create User."

You can use the article below as a reference.

Add a user or group on Mac - Apple Support

If you are experiencing the issue when signed in on a different user account, please check if the issue persists while on safe mode. Safe mode prevents certain software from loading as your Mac starts up. Performing this step may help resolve the issue, or further isolate the issue.

Below is an article to help guide you through the process.

Use safe mode on your Mac - Apple Support

If the issue persists after trying the steps above, the next best step is to have the device inspected by a technician.

You can explore your service options here: Get Support

If your device is considered vintage or obsolete, please check out the article below.

Obtaining service for your Apple product after an expired warranty - Apple Support

Take care!