I encountered this use case before as well and thought it would be an easy fix - it was not possible.
My journey allowed me to discover that this value is stored as <Count>160</Count> in the session .qfx file which is essentially and XML formatted file. XML nodes values can be easily altered via automation using PowerShell for example. Unfortunately simply changing this value prior to opening the session in QuickFields does not work. Several other XML nodes are updated when QuickFields saves a session regardless of any changes made. These include XML nodes like <security bits>, <ProfileId>, <CipherValue> and <ParentKey>. If you open an .qfx file, change nothing, and save it these nodes are updated and ensure the integrity of the session which is good but bad for externally modifying the file. That is where my investigation stopped as those would require more intimate knowledge of Laserfiche algorithms that calculate those node vaues.
Sorry that doesn't help you in your quest for a solution but I found the adventure interesting enough to share.