(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
In Spider Project it is possible to set periods with different productivity of assigned resources.
Productivity [Start] shows initial productivity,
Productivity [Current] shows productivity at the data date.
These fields are calculated together with cost calculation.
Actual productivity is calculated for each assignment and it can be different for different activities of the same type.
The reasons for productivity deviations must be studied.
I would not recommend to use past productivity automatically for future activities scheduling.