Many thanks. But I searched and I could not find one which specifically showed how you solve the problem of already having an Electrum wallet in an old PC and wanting to make sure your coins are only on your new PC and not accessibly anymore on the old PC.
Use the magnifying glass you can find it on the left side of the search box above because the search box above is limited compared to Google search.
If you install Electrum and created a new wallet on this new PC it shouldn't be accessible from your old PC unless you restore your old wallet to your new PC.