I have set several Tempo/Time Signature,
then I want to insert some at the beginning,but it seem that it's unconvenient Tampo/Time Signature move along.
If you want the tempo/timesig markers to remain at their original *time* positions:
* If the new tempo marker causes partial measures, make sure that the first timesig marker after the new tempo marker is set to "Allow partial measure before this marker", otherwise that timesig marker will change its time position and jump to the next measure start.
* In project settings, set the "Timebase for tempo/time signature envelope" to Time.
If you want the tempo/timesig markers to remain at their original *beat* positions (counted as the number of quarter notes from project start), set their timebase to Beats.