I am trying to make an action for my homebrew subclass, but rather than it display as a saving throw, it keeps showing as an attack roll in the character sheet. How do I solve this?

It could be a couple things, so your best bet is to look at the pinned posts on this forum (How-To's and Tutorials). I can provide something more concrete if you post a screenshot of what your action page looks like, but my best guesses would be to make sure your "Action Type" dropdown is set to "General" and the "Attack Range" dropdown is not set to anything ("—").

This was it, I had the attack type set to ranged. Is there a way to have its range in the character sheet show it as a cone? Like how spells do?

I recommend checking out the pinned posts I recommended for full details, but my off-hand guess would be to set "Action Type" to "Spell", then select "Cone" form the AOE dropdown and specify the range of the cone in the textbox next to that one.

Quote from Razmus >>

I recommend checking out the pinned posts I recommended for full details, but my off-hand guess would be to set "Action Type" to "Spell", then select "Cone" form the AOE dropdown and specify the range of the cone in the textbox next to that one.

 
That would set the range for the origin point of the cone, leave it blank and it’ll effectively set the origin point as the caster. To set the actual size of the cone you have to designate an area effect size.