Schneider 4048 a/c output voltage too high

[Alpine_Junky]

Schneider SW4048 a/c output voltage too high - around 128-129 vac. Triggering random warnings that exceed the default 135 vac setting when a larger load is applied (microwave). I can't find any way to adjust the voltage output on the inverter down. Past threads here asking about it without resolution.

Any ideas? New inverter so I don't want to trash it just yet... I know, I know.