When I insert plugin to one insert it copies to all midi track

Please help!
When I import a midi song to cubase,it desolves al parts and I have multiple instruments there!
Now, when I insert a plugin to one midi track it doubles and copies one plugin to all my track
How to disable this,thanks!! And sory on bad english

Ho alexx2409,

Thanks for your message and welcome to the Cubasis for iPad forum.

Please clarify, if you’re talking about Cubase (for Win/macOS) or Cubasis for iPad - which this forum belongs to!

In regards to MIDI file handling in Cubasis for iPad:
Cubasis supports to import/export MIDI files (MIDI File Format 1 for export).
Please make sure to import MIDI files that are format 1, to have the events laid out to individual tracks in Cubasis.

Please let me know if this helps.