(British English and American English have different rules for the use of the present perfect. The comments being made here and the exercises state the correct grammar for British English. However, in American English, it is often considered acceptable to use the past simple in some of these examples.)
We use the past simple to talk about actions in the past that have finished. It talks about 'then' and definitely excludes 'now'.
We use the present perfect simple to look back on actions in the past from the present. It always includes 'now'.
These sentences are in the past with no connection to the present.
Now look at these same situations seen from the present.
Typical time phrases that we use with the past simple are 'yesterday', 'ago', 'last year', 'in 1999'.
Typical time phrases that we use with the present perfect are 'ever', 'never', 'since'.
Typical time phrases always used with the present perfect in British English but often used with the past simple in American English are 'already', 'just', 'yet'.
The time phrase 'for' can be used with both forms, but with different meanings.