Well, no, there's no setting, it most likely comes down to a combination of things.
First of all, 802.11n Wi-Fi is limited to about 30-35Mbps when using a single channel which is what is done when the Almond is in range extender mode, as one channel talks to the main router and the other sends the signal on to whatever devices you have connected.
Secondly, the speed will be very dependent on the distance between the range extender and the main router/access point, just like any other Wi-Fi device. It'll also depend on what's in between (metal, concrete etc.) and even the orientation of the Almond will matter to a degree to the signal. As such, you might want to move it around a bit and see where you can achieve better signal.
Wi-Fi isn't an exact "science" and I'm suffering from the same "problem" in my home as it's a lot of metal and concrete in the floors and walls which not only reduces the range, but also the speed. I found that I had to move my Almond that's set up as a range extender around a bit until I found a spot with good signal. Even so, I'm seeing around 10-14Mbps and I consider this pretty good, especially as my previous range extender would deliver 1-2Mbps at the same spot and it had rather large external antennas.