When you open a connection to a TWAIN device, the device may reset its properties to default values or load properties from a profile. This is normal behavior for a driver.
DotTwain (Desktop Scanning)
If specific settings are required for your application, you will need to set the capabilities after each call to open the device. This includes using SaveParameters / SaveXmlParameters methods of the Device object to store settings, and using the LoadParameters or LoadXmlParameters methods to retrieve them later . (which you use depends on whether the scanner can handle custom properties) for more see
HOWTO: Proper use of Save/Load Parameters in TWAIN scanning
WingScan (Web Based Scanning)
For WingScan, we do not have a bulk load/save, so you'll need to store the settings values /configurations using text, xml, json, etc.. and then parsing your stored settings yourself to set up the WingScan scanningOptions configuration, or applying the options between scans
HOWTO: Change WingScan Scanning Options Between Scans
Q10142 - FAQ: Why do Scanner Settings Change/Reset Between Sessions?