UNICOM Electric 8 - Manual (Page 56)

View spanning tree information about the Root Bridge on this screen.
View spanning tree status about the switch here.
Parameter Description
Priority
You can change the priority value, a value used to identify the root bridge.
The bridge with the lowest value has the highest priority and is selected as
the root. Enter a number 1 through 65535.
Max Age
You can change the Max Age value, the number of seconds a bridge waits
without receiving Spanning-Tree Protocol configuration messages before
attempting a reconfiguration. Enter a number 6 through 40.
Hello Time
You can change Hello time value, the number of seconds between the
transmission of Spanning-Tree Protocol configuration messages. Enter a
number 1 through 10.