2 or 3.
Student or Learner
Can one say
a. They have to make changes for the time their manager will be absent.
Does that mean
1. They will make changes during that period and the changes will remain effective even after the manager comes back
2. They will make changes during that period that will remain effective until their manager comes back
3. The changes will all be made now and will remain effective till their manager comes back
I'd say #3. If it were #2, it would say during the time, not for the time.
It's hard to be sure of the meaning, because it's an awkward sentence.
I'm not a teacher. I speak American English. I've tutored writing at the University of Southern Maine and have done a good deal of copy editing and writing, occasionally for publication.