I looked in the manual. It appears there is 2 settings in the menu.
it is 8ohm and 6 ohm. under the chart, it looks like if set to 6ohm. The fronts impedance is min 4ohms, while all other channels' min impedance is 6ohm. So it looks like the receiver does work.

I have just bought this receiver less than a month, so I will not be upgrading anytime soon. This receiver is same as the RX-V1800.

So is it ok to mix impedance on speakers? Would it be suggested to buy the M60 instead? My room is about 17ft long x 12 ft. I have just bought the M22 for my surrounds. I am planning on buying the M80 for fronts and the VP150 as center along with another set of M3 as my surround backs.

I just want to make sure my receiver will be able to handle it.

any suggestions?

An amateur built the Ark.
Some professionals built the Titanic.
But Noah took a little advice.