I don't know but found a similar question answered here. I take Jeff Wrights answer to mean that ones preferred language must be selected at time of installation - not afterward. At least as it was in the days of PSE8. Again, I'm not certain what your options are for PSE 2020..
Yes, you are asked your choice for the language at the time of installation.
That means that you have first uninstal, then reinstall. Watch carefully the dialogs to avoid missing that installation step.
Uninstalling and reinstalling on the same computer does not requireyou to 'sign out' before uninstalling and 'sign in' with your licence key if you are on the same maching, but you may feel safer. See the menu 'Help' for signing in and out.