how do I convert a scanned color negative into a positive on photoshop?

APPLE-I works to convert Negative color to Positive color.  OS10.15.4 using Photoshop Elements

The Invert command will typically not do the job on its own for a color negative. This is because color negatives have an amber mask that will become a blue color cast after inverting, so the inverted color negative will not have the proper colors.

The best place to convert a color negative is usually at scan time with the scanning software. Many scanning applications have a good color negative conversion feature built in, and some have profiles for specific types of color film to remove the amber mask more effectively. This is the preferred method because the image comes into Photoshop positive and ready to use.

If your color negative is already in Photoshop, you can invert it as a first step, and then use a Curves adjustment layer to eliminate the mask color using a curve in each channel. You can find various tutorials for this around the web. But it takes a lot more time than getting it right at the scanner.

Try This

I have not tried this command on a negative,but it's Ctrl i (PC) or Cmd i (Mac) for Invert Colors.