Hello,
You can use the Inventory Valuation report that will surely give you the correct inventory quantities and values, but you will need to use Filter totals by location if you want to filter values by locations. You can see increases and decreases in the period from start to end date, quantities on Start and End Date.
For quantities on purchase/sales documents, I would recommend the next solutions.
If you want to see information for one item, then go to the Item Card and in the Inventory tab, you will see quantities listed by orders.
If you want data for all items on all purchase or sales documents then I would recommend that you open the Sales Order card, select a line on the sales order, and then click Ctrl+Shift+F1 (page inspection) and then View table. Depending on your permissions or BC version you could do this, which will open you a table of all sales document lines. The procedure is same for purchase documents.
You will see which document type is that row, and all other information from lines of sales documents. Export to excel and enjoy. :D
You can try also Inventory Availability or Inventory Reorder, depending on your needs, but I will also recommend you to check the quantity for one item for all reports because sometimes filters for locations or dates can't do their job on Item ledger entries.
If you have any other questions related to this answer fell free to ask,
Greetings.