Change signs in a squared equation in Maple

I want to change the signs of all symbols in a squared equation in Maple. For example, these equations yield identical answers:

1. ((-a + b - c + d)^2) / (a - b)
2. ((a - b + c - d)^2) / (a - b)

Now let's say I have coded the first function in Maple using:

test := (-apple + banana - cherry + date)^2/(apple - banana)

I can then easily swap these with:

numer(test)/denom(test), because the numer() changes the signs.

However, if I use different labels, such as swap "apple" with "quality", this doesn't work anymore.

test := (-quality + banana - cherry + date)^2/(apple - banana); numer(test)/denom(test)

Could you explain why and how it can be achieved instead?

Here is one way to handle your examples,

It acts on all squares of sums in the expression. It maps - across the sum subexpression.

sw:=e->subsindets(e,`+`^2,
                  u->subsop(1=map(`-`,op(1,u)),u)):

expr:=((-a+b-c+d)^2)/(a-b):

sw(expr);

   (a-b+c-d)^2/(a-b)

 test:=(-quality+banana-cherry+date)^2/(quality-banana):

sw(test);

   (quality-banana+cherry-date)^2/(quality-banana)

Here's a variant on that.

sw:=e->subsindets(e,`+`^2,
              u->map(`-`,op(1,u))^2):

You could also make it work on other even powers.

sw:=e->subsindets(e,`+`^even,
              u->map(`-`,op(1,u))^op(2,u)):

expr2:=(a-b)/(-a+b-c+d)^4:

sw(expr2);

   (a-b)/(a-b+c-d)^4