Adverb??

Why adverb sometime place behind the verb and sometimes place after the verb? Like this
-We should use our time wisely.
And...
-He exactly indicated the problem.

I am just confused.
Can't I just change it like this...

We should wisely use our time.

He indicated the problem exactly.(although it sounds weird...)

I learned adverb is always behind verb(except is am are etc.) in grammar book.