(Argument for whenever Chara addresses “you” they are addressing Frisk.)
Whenever the narration, who is strongly suggested to be Chara, uses the pronoun “you” they use it in reference to Frisk not the player. (However there is also proof that they are at least aware of the players presence/influence)
(possibly mocking the player’s limited viewpoint)
(We the Player have been in literal control of Frisk the whole time)
There is also this bit of contrasting dialogue:
This isn’t in reference to the player who at this point may or may not have named Chara after themselves
(Note :the following pic is from my mom’s unfinished run)
This is in reference to the fact that Chara and Frisk are two separate people, as established in the True End.
So yeah, whenever Chara says “you” they are talking to Frisk.
((And when Flowey talks to Chara at the end they are talking to Chara, who in turn we the player can act through to perform a “True Reset” and play the game again.))