I currently have one switch that controls 3 lights (2 exterior and 1 interior). I would like to have the exterior lights on one switch and the interior lights on a separate switch.

Inside the switch box, there are 3 electrical lines - 2 with white & black, 1 with red, white and black.

All the white wires are capped together.
The red wire is attached the top of the switch.
A black wire is attached to the bottom of the switch and then is capped together with all the black wires.

Inside the interior light fixture box, there is a white wire and a blue(!) wire.

I am unable to open the exterior light fixture boxes as they are out of my reach.

How can I re-wire so that the exterior lights are on one switch, and interior light is on one switch?

Thanks.

I have attached a drawing of the existing wiring within the switch box.

Disconnect the four black wires under the wire nut. Then connect each black wire to the black from the switch one at a time and see which lights burn. When you have identified which wire goes to the outside reconnect the other two back to the black from the switch.
Get another switch (or a 2-in-one switch). Remove the red wire and connect two black pigtail wires to it with a wire nut. Connect the pigtails to the switches. Connect the black wire that goes to the outside light to the new switch.

If you use a 2-in-one switch you will just connect the red to the side that has only one screw, connect the black (currently connected to the switch) to one screw on the other side and the black to the outside light to the other screw.

Thanks so much, Harold. I was hoping that you would answer. Your answers to other questions have helped me on other electrical problems. My drawing was inspired from the ones you have created for others.

Thanks again!

You are welcome. Thought the switch symbol looked familiar.

I wonder if there is other wiring out from those wires that the black may be the hot(comming into the box, 1 leaving the box, and a hot going up with the Red? Switchleg.
Hk is likely right, have seen many combinations.
With the switch turned off, you could look for voltage on the red and black to verify before dissembly. If the black is the Hot, I would separate all blacks and see which is the feed and identify, then apply power to each of the blacks to see which is going where.
Worse case, you may need to get a cable to 1 of the lights(easiest one).
Good Luck