As we age it seems the songs we learned when we were younger stay with us better.
Now, I need prompt sheets regardless of how much practice time I employ.

Another problem for the musician is that the music can distract you from the lyrics especially if you are playing with good accompanists. or sometimes bad accompanists.

here's how I have to do it. Repeat each line of a stanza at least twenty times in a row.
(This is how some foreign language schools teach vocabulary)   The piece together the lines of the stanzas and recite the stanzas at least twenty times in a row.

I find writing out the lyrics doesn't do me much good because I tend to be an aural not a visual person.

Frank