you need to export the products first, 

1. Select the items you need to export (using the tickboxes)
2. 1. If you have over 10000 items to selected to export, you will only see the option to "select all 10000". You can see the total number selected by clicking the 10000+ (to the right of favourites).
3. Selecct actions > export
4. Select the data columns that you need to export
5. 1. make sure that you use the tickbox at the top "I want to update data (import-compatible export)" this will add all the data field names and the first column will be the ID, the others make importing simple.
6. Save the export and edit the data, making sure that columns "id" stays included in the data.
7. 1. The "id" data is the key to updating data in Odoo. Odoo allows you to have multiples of the same product with the same SKU, or multiple vendors of the same product (but automatic purchasing rules will always choose the first / top vendor in the list)
8. import the updated data
9. 1. try a small sample first and keep your original exports because to make errors is to be human.

Notes

• If you want to update your Selling & Cost prices, the export / import from: 
  Inventory > products > Products.
• If you want to update your purchasing pricing, then export / import from: 
  Purchase > Configuration > Vendor Pricelists

Hello.

I would like to suggest you to use Advanced Price Rules in case you have a similar rule for all updated prices.

You should create new pricelist using following process

Finally new Pricelist will automatically apply to all sales orders.

Hope, you will find this information usefull.

Good luck.