How to change rate of an interface in mikrotik ?

I have a problem with mikrotik because i’m a beginner.The problem is that i don’t know if i can change the rate of an interface,currently is 100Mbs but i want to change to 1Gbs if possible.I want to sent the second mikrotik more than 100Mbps.I connect to second mikrotik via a Multiplexer.My first router is CCR 1016-12g and can support 1gbps and the second router is CCR 1009-8g-1s and that it seems that support 1Gbs per interface.Whats the problem ?

Not familiar with your devices, but generally if you connect to the device, click on “Interfaces” then select “ethernet”, you should be able to make the changes there. Your cable must also support the speed.

well i am not sure where to change it.Should i turn off Auto negotation and other advertise except 1Gbs ? Thanks

What’s a “Multiplexer”?
I expect that is the source of your problem. You need all 8 wires connected correctly in the cable for it to work at 1Gbps.
Don’t mess around with the config. on the routers - it probably won’t achieve anything. Auto should work.

Thanks alot.