Here's and example of what I'm trying to do

Say I have a book by the name.... 'Eating Apples' is cell A1, and next to it
i type the numbers '1234' in cell B1. Right, what I'm trying to do is that if
I type the number 1234 is any cell in any sheet hereafter, the Title 'Eating
Apples' would pop up, replacing the numbers 1234.

Basically what I'm trying to do is linking the numbers '1234' to 'Eating
Apples', so that if someone wanted to type down 'Eating Apples' in any other
cell, they dont have to do that, instead they just have to type '1234' and
the title 'Eating Apples' would replace those digits.

Does this make sense? Is this possible on Excel?

Thanks for any help guys :)