different basevalue for stems in a for loop

I am stuck on how I can reset the multiple stems' BaseValues in a for loop.

However, when I run my code, the BaseValues of stem1 to stem11 switch from 0 to -y_shift after some time. Is there a way where I can reset the BaseValues of my stems to be at the right BaseValues?

stem1 to stem11 should have a BaseValue at 0.

stem12 should have a BaseValue at -y_shift.

y_shift = 1;

for k = 1:10:m+1 % for faster animations i.e. skip frame
    z = u_approx_dirac(k,:);
    clf
    hold on
    plot(x, zeta(x), 'r');
    if t(k) < x_dis(1)
        u(k) = u_approx(2,3)*sqrt(zeta(c)/zeta(c+t(k)));
        stem1 = stem(t(k), u(k), 'filled', 'k');
        set(stem1, 'ShowBaseLine', 'off');
        plot1 = plot(x_dirac (abs(z) < z_min), z (abs(z) < z_min), 'k');
    end
    if x_dis(1) < t(k) && t(k) < x_dis(2)
        u(k) = (1 + r_dis(1))*u_approx(2,3)*sqrt(zeta(c)/zeta(c + t(k)));
        stem2 = stem(t(k), u(k), 'filled', 'k');
        set(stem2, 'ShowBaseLine', 'off');
        plot2 = plot(x_dirac (abs(z) < 2), z (abs(z) < 2), 'k');
    end
    if x_dis(1) < t(k)
        u(k) = r_dis(1)*u_approx(2,3)*sqrt(zeta(c)/zeta(2*x_dis(1) - c - t(k)));
        stem3 = stem(2*x_dis(1) - c - t(k), u(k), 'filled', 'k');
        set(stem3, 'ShowBaseLine', 'off');
    end
    if x_dis(2) < t(k)
        u(k) = (1 + r_dis(2))*(1 + r_dis(1))*u_approx(2,3)*sqrt(zeta(c)/zeta(c + t(k)));
        stem4 = stem(t(k), u(k), 'filled', 'k');
        set(stem4, 'ShowBaseLine', 'off');
    end
    if x_dis(2) < t(k) && t(k) < 2*x_dis(2) - x_dis(1)
        u(k) = r_dis(2)*(1+r_dis(1))*sqrt(zeta(c)/zeta(2*x_dis(2) - c - t(k)));
        stem5 = stem(2*x_dis(2) - c - t(k), u(k), 'filled', 'k');
        set(stem5, 'ShowBaseLine', 'off');
        plot3 = plot(x_dirac (abs(z) < 2), z (abs(z) < 2), 'k');
    end
    if 2*x_dis(2) - x_dis(1) < t(k) && t(k) < 3*x_dis(2) - 2*x_dis(1)
        u(k) = -r_dis(1)*r_dis(2)*(1 + r_dis(1))*sqrt(zeta(c)/zeta(2*(x_dis(1) - x_dis(2)) + c + t(k)));
        stem6 = stem(t(k) - 2*x_dis(2) + 2*x_dis(1), u(k), 'filled', 'k');
        set(stem6, 'ShowBaseLine', 'off');
        plot4 = plot(x_dirac (abs(z) < 2), z (abs(z) < 2), 'k');
    end
    if 2*x_dis(2) - x_dis(1) < t(k)
        u(k) = r_dis(2)*(1-r_dis(1)^2)*u_approx(2,3)*sqrt(zeta(c)/zeta(2*x_dis(2) - c - t(k)));
        stem7 = stem(2*x_dis(2) - t(k), u(k) , 'filled', 'k');
        set(stem7, 'ShowBaseLine', 'off');
    end
    if 3*x_dis(2) - 2*x_dis(1) < t(k)
        u(k) = -r_dis(1)*r_dis(2)*(1 + r_dis(1))*(1 + r_dis(2))*u_approx(2,3)*sqrt(zeta(c)/zeta(2*(x_dis(1) - x_dis(2)) + c + t(k)));
        stem8 = stem(t(k) + 2*x_dis(1) - 2*x_dis(2), u(k) , 'filled', 'k');
        set(stem8, 'ShowBaseLine', 'off');
    end
    if 3*x_dis(2) - 2*x_dis(1) < t(k) && t(k) < 4*x_dis(2) - 3*x_dis(1)
        u(k) = -r_dis(1)*r_dis(2)^2*(1+r_dis(1))*sqrt(zeta(c)/zeta(4*x_dis(2) - 2*x_dis(1) - c - t(k)));
        stem9 = stem(4*x_dis(2) - 2*x_dis(1) - t(k), u(k) , 'filled', 'k');
        set(stem9, 'ShowBaseLine', 'off');
        plot5 = plot(x_dirac (abs(z) < 2), z (abs(z) < 2), 'k');
    end
    if 4*x_dis(2) - 3*x_dis(1) < t(k)
        u(k) = -r_dis(1)*r_dis(2)^2*(1 - r_dis(1)^2)*u_approx(2,3)*sqrt(zeta(c)/zeta(4*x_dis(2) - 2*x_dis(1) - c - t(k)));
        stem10 = stem(4*x_dis(2) - 2*x_dis(1) - t(k), u(k), 'filled', 'k');
        set(stem10, 'ShowBaseLine', 'off');
    end
    if 4*x_dis(2) - 3*x_dis(1) < t(k) && t(k) < 5*x_dis(2) - 4*x_dis(1)
        u(k) = (r_dis(1)*r_dis(2))^2*(1+r_dis(1))*u_approx(2,3)*sqrt(zeta(c)/zeta(4*x_dis(1) - 4*x_dis(2) + c + t(k)));
        stem11 = stem(t(k) + 4*x_dis(1) - 4*x_dis(2), u(k), 'filled', 'k');
        set(stem11, 'ShowBaseLine', 'off');
        plot6 = plot(x_dirac (abs(z) < .5), z (abs(z) < .5), 'k');
    end
    plot7 = plot(x_dirac(x_dirac > t(k)), 0*z(x_dirac > t(k)), 'k');
    
    % plotting reflection
    time = t(1:2:k);
    reflection = reflectedwave(y(1:2:k));
    plot8 = plot(time (abs(reflection) < 2), reflection (abs(reflection) < 2) - y_shift , 'b');
    stem12 = stem(time (time == 2*dis(1) - 2*delta | time == 2*dis(2) - 2*delta), 2*delta*reflection (time == 2*dis(1) - 2*delta | time == 2*dis(2) - 2*delta) - y_shift, 'filled', 'b', 'ShowBaseLine', 'off');
    set(stem12, 'BaseValue', -y_shift, 'ShowBaseLine', 'off');
    legend(sprintf('t = %.6f', t(k)));
    grid on
    xlim([c d]);
    xlabel('x');
    ylim([-2 2]);
    pause(0);
    hold off
end