There some data types named count, I can not change it to sum. but I can see that in videos it can be changed
Is this the issue you contacted me via mail yesterday, please?
Hope it is solved now.
The COUNT field can’t be aggregated differently. You are able to use it in Table Calculations and LOD calculations. You can also create a new calculated field with the value 1, which effectively counts the number of records in your data. See here for full details on using the COUNT fields and replacing it.