Price Variation for the products in inventory

[yamamaa]

So the price keeps varying everytime , as if its taking a market price . 
I want to stop this 
as well as when the customer orders a product, the price is increased . can you help me sort out these 2 issues 

[MaxDesign]

Can you link your store? It is impossible to understand what is going on on your store unless we have a look at it. Maybe it is an app that converts price currency?