I'm trying to create a homebrew, both a main race and a subrace.  However, I can't figure out how to get a trait from a subrace to replace a trait from the main race.  Using mine for example, the Salamanderfolk, they have a trait called Strong and Durable, where they can choose a proficiency in either Strength, Acrobatics, or Intimidation.  I want the subrace, the Axolotlfolk, to have an ability called Enhance Instincts, which replaces Strong and Durable by letting players choose proficiency in either Survival, Nature, or Perception.  When I try to mark a trait as a Replacement, it only shows traits from the Axolotlfolk's traits, rather than everything.  And when I try to make a character to test, both traits show up when I only want one or the other.  Is what I'm asking even possible?  I hope I explained what I'm trying to say well enough.

That’s because you are accidentally trying to use the tools to make “optional lineage traits” like from Tasha’s Cauldron because when the DDB Devs implemented that crap they used the same terms for things that they were already using for other things. All of your features should always be “granted,” never “additional” and never “replacement.”

Subrace traits never replace parent race traits, they only ever add traits. You can never actually pick a parent race like “elf,” so someone liven subrace features never have to replace any, they just add additional traits.

Variant races (like Half-Drow) have traits that replace traits from the original because the original base race (like Half-Elf) can be chosen for a PC all by itself.

Basically, you have confuzzled the difference between a Subrace and a Variant Race and DDB has made it worse by using the same terms to mean completely different things and haven’t explained them well.

Thank you, I see what you mean.  Is there anyway to get the traits replaced by a variant race to not show up in the builder when making a character?

That’s what the “is called out” checkbox is for if I understand it correctly.