Hi Mahsa,
The initial condition must be set for entire 1D model of the river network, not only for "(upstream) as local values". You have to set up a general value to be applied for the whole system of branches and other values for specific sectors, if the case.
Also, you have to understand the distinction between "Water level" and "Water depth" for the field Level type and chose the apropriate value (eg. Water depth = 1 m as a global value and Water level = 132.40 m (could be a normal retention level) for a specific sector of a certain river where a reservoir is located - please, see the image attached.
Kind Regards,
Aurelian