Electric potential

Electric potential is what is left when you divide the charge out. Park a test charge at a point, ask how much electric potential energy the system has because it is there, divide by the size of the test charge. What survives belongs to the location.

Volts, not joules. One volt is one joule per coulomb. A 2 C charge at a point where $V = 5$ V has $U_E = 10$ J; swap it for a 1 C charge and the energy halves while the potential does not move at all. Potential energy is a property of a charge in the field. Potential is a property of the field.

$V$ against $\Delta V$. Potential is a value at one point, measured against a zero placed at infinity by AP exam convention. Potential difference is the change between two points, and it is the quantity you actually compute with: the sheet prints $\Delta U_E = q \Delta V$. Everyday "voltage" almost always means a potential difference, which is why a 9 V battery has a 9 V gap between its terminals rather than a potential of 9 V.

Potential is a scalar. It superposes as signed numbers, $V = k \sum q_i / r_i$, with no components and no angles, and it falls off as $1/r$ while the field of a point charge falls off as $1/r^2$. The exponent on that $r$ is 1, not 2. The electric field and potential guide works the arithmetic.