The preset class rules have to be one of the most asinine things about the VicTec / Shibby branches. Just delete all of them and make your own. To also help reduce confusion I rename them with standard names like original Tomato has.
After you have done the above, a starting point for QOS control of the other computers is to make a controlled speed class. The first thing to do is to set the maximum inbound and outbound reference values to 110% of your actual bandwidth ( this is on the QOS Basic page ). Next set the default class to "Medium" ( the 3rd class down on the list ). Set the outbound rates for "Medium" class to 5 - 50% and the inbound rate to 75%. Set outbound rates of "Highest" class to 100% - 100% and inbound rate of "Highest" class to 100%.
On the Classification page make two rules to match your computer using the IP address ( set your computer with a static address ). Make one rule that matches packets to your computer and one that matches packets from your computer. These are named "SRC IP" and "DSP IP". For the protocol select "Any Protocol". Assign these two rules to use "Highest" class. Now all traffic to and from your computer will have no speed restriction applied and everybody else on the network will have the allocation as defined by the "Medium" class. Your computer will be able to push outbound packets of other computers down to 5% from 50% if needed.