I can see why it feels hard. Almost all these symbolism tropes refer to a specific existing symbolism, rather than ways to create something new. So what are your options?
Apples have other symbolic meanings if you look to the right traditions, and if you know what you're doing you can create something new. One of my stories is called Golden Apples , even though apples per se are essentially irrelevant to the plot, because they are very much a symbol. The protagonist manages to get into a special school, where golden apples are free at lunch. This is in reference to the apple of discord in the myth of <PERSON>: the students will be head-hunted when they're older, and they're only their because of previously competing over places in much the same way. 805
(It's also a reference to the way genetics and environment interact in both apple colour and student attainment.)
She receives a necklace with an apple depicted on it; at first this seems like a simple gift praising her intellect (an apple is of course a Biblical symbol of knowledge) over her family's poverty (which also forces her to overcome certain struggles in the story), but then she discovers a secret in the clasp as nefarious as the Greek apple's intent. This gets her embroiled in darker events than she would have expected, which again calls back to the Biblical significance. So in a story about different ways gifted children are educated - a topic which seems to relate to neither Biblical nor Hellenic beliefs - I create a complex, layered symbolism through a combination of the title, references to multiple older works, plot events (including ironic variants on earlier ones), and in-universe attitudes.
Of course, readers are entitled to think my specific construct is stupid.
Another way I like to create symbolism is through ambiguous foreshadowing. Another of my stories is called Thrust . An early line gives the impression this is a reference to greatness, and possibly other things, being thrust upon certain people, because the protagonist is both talented and arrogant, and she uses her talents in selfish ways. But later in the story, the one-word title becomes apposite to multiple other events in her life, basically with respect to every meaning thrust has. I haven't finished writing it yet, but the ending I intend will call to one very specific meaning the rest of the story overlooks - and, also, to the first one considered. 59