Settings are available from X-Plane's menu:
Plugin > LiveTraffic > Settings.... In the "Advanced" tab you can tweak some rather internal parameters of LiveTraffic, which you should definitely understand before changing.
Amount of information written to X-Plane's log file
In case you can reproduce an error or weird behaviour then please set this to Debug before your reproduce once more. Then create a support request and attach the resulting log file.
Level of messages shown in the message area in the top right corner. Fatal shows least, Info most messages.
Only selected messages appear there at all. With this setting you can further reduce the number of messages appearing. Less than Warning is not recommended, however.
Max number of aircrafts
Maximum number of aircrafts to follow.
Max number of full a/c to draw
Maximum number of aircrafts to draw "in full", i.e. as an aircraft object. If there are more aircraft available to draw then for the others, those most far away, only their lights will be drawn. Reducing this number can help improving performance on slower machines while not affecting visiual impression much.
Max distance for drawing full a/c
Distance in nautical miles for which to draw "full" aircraft as opposed to lights only.
Distance in nautical miles around current viewing position which is scanned for live flight data. Note that the channels require this value to be converted to kilometers when requesting tracking data, so some rounding occurs.
Snap to Taxiways
Aircraft positions will be updated to the closest taxiway or runway centerline, if there is such a taxiway/runway in a maximum distance of this many meters.
Live data refresh
Number of seconds to wait between two queries for live flight data.
Note that data for any one aircraft does not update continuously. Querying data more often will not have much of an effect.
Seconds to buffer before displaying aircrafts. This serves as the look-ahead buffer for LiveTraffics data cleansing and take off/landing prediction and is equivalent to the time lag between LiveTraffic's aircraft display and reality. (See an FAQ for more background.)
Values less than 90s might already lead to decreased LiveTraffic's ability to smoothen data inconsistencies and are not recommended.
Strictly speaking is this the time frame LiveTraffic requires data for before it displays an aircraft. Tracking data comes with a timestamp, that is relevant here: If one query returns an old position from then 70s ago, and the next query, 20s later, returns a new up-to-date position, then the difference between these two positions is 90s and LiveTraffic starts showing the aircraft.
a/c outdated period
If there is no data for this number of seconds then the aircraft is removed from display.
This setting should be greater than the Live data refresh period, otherwise aircrafts have no chance of collecting enough data for display.
Also see a FAQ on that.
Number of seconds a network request is allowed to take before considering it failed.
Note that OpenSky is known to sometimes respond sluggishly, taking up to 60s. Hence values below 60s are not recommended if using OpenSky for tracking data.