E0 value confusion

basically i watched two vids and they saying different things.
for an equation like this A+ + e- > A and let say the E0 value was originally-0.90 if i was to increase the concentration of A+ would E0 be more negative?

No. E_A would become more positive, hence E_cell would become less positive.

You can think of the cell potential as an equilibrium constant. As you increase A⁺, the equilibrium will shift to the right. We know with normal equilibrium theory that as the equilibrium shifts to the right, the equilibrium constant becomes more positive. It works in exactly the same way here - the equilibrium shifts to the right so E_A becomes more positive.

You can also think of it this way - if [A⁺] increases, then according to the equation, more electrons will reduce the increased amount of A⁺ and so less electrons will be in the system. Since electrons are negatively charged, less electrons in the system will make E_A more positive.

This will only be the case if the electrode potential of the other half-cell is less negative.

For example:

A⁺(aq) + 1e <==> A(s) ....... Eº = -0.9 V
Li⁺(a) + 1e <==> Li(s) ...............Eº = -3.0 V

Cell potential = 2.1V

if A⁺(aq) is increased the value of E_cell becomes LESS negative and the cell potential increases.