Hi! Most likely your tap water had CO2 in it and after that had a chance to off-gas the pH is higher. To see if this is the case, leave a glass of water out for 24-48 hours and then test the pH. If you have shells or coral pieces in your tank that can also raise pH. Some rocks can as well.
Driftwood or Indian almond leaves can be added to naturally lower pH. They may also make your water slightly brown.
You could also add RO/DI water to your tap water, say half and half.
It may be easier to just choose fish that are okay with that pH. Live-bearers, for example, will be fine.