Painting - Wrong paint on doors and trim

My mother painted all our interior doors and trim with Martin Senour Interior Latex Satin Gloss Enamel. It didn't work well. The
new paint looks very flat on the old paint (not as shiny). And there are patches where it's coming off. What did she do wrong
and most of all what do I need to do to fix it. We're not sure what
was originally painted on the doors and trim as they were painted
when we bought the house in 1966. I'd appreciate any help that
could be offered.

Satin is not as shiny as semi-gloss. Then there is gloss. That may be your disappointment. Applying the paint too thinly can cause reduced gloss.

Patches where the paint is coming off may result from the surface not being cleaned before painting. Hand oil is almost as bad a cookiing grease for invisibility and resistance to paint. Lightly sand off the failing areas and feather into surrounding good paint. Clean with mineral spirits, then prime and paint.

Hope this helps.

It had been cleaned thoroughly before painting. Right now we're
leaning toward sanding and repainting. Are you sure it isn't worth
finding another oil based paint (like Sherman Williams or Valspar)
rather than staying with the Latex Satin Gloss?

Using latex or alkyd paint is a matter of personal preference.

Paint fails to adhere because no bond was formed. A clean, dry surface is necessary, primer may help with the bonding on a marginal surface, such as flaking or chalking or contamination.

In your situation, I would scuff sand the entire area and prime with Zinsser or Kilz to ensure that the surface is stable, then paint. The extra step of primer even over a painted surface may prevent problems later.

Thanks, I will.