Hi
VEL ASSA,
Icon shape, theme colour are changed to default during usb connection with pc / laptop--> Does this behavior appear every time? We didn't find the same behavior on our device. Please tell us which USB preference you chose.
network signals are lost in both sims.-->
Please try resetting your network settings and try again. (Settings > System > Advanced > Reset options > Reset Wi-Fi, mobile & Bluetooth)
Please tell us your mobile network provider
Please show us a screenshot of the Settings>SIM cards
Please change to another SIM card by another network provider, and check if the problem still appears.
Please also put your SIM card into other phones and check if the problem appears.
