You need to associate the field in section access to the source data.
Please refer here and see if it helps
Identify the lowest level of data and associate the field to section access script in QlikSense.
There is no option in QlikSense to enable/disable security.
Also another note, section access will work only in enterprise version and not in desktop.
See below script for reference
LET vLevels=Len(KeepChar(vHierarchyDef,',')) + 1;
LOAD * INLINE [
ACCESS, USERID, REDUCTION
USER, US\SALIDINA, ILLINOIS
USER, US\SREEDENON, TEXAS
USER, SK, CHICAGO
For vAncLevels= 1 to vLevels
UPPER([$(vAnc)]) as REDUCTION,
Notes from above script
1. This script will reduce the data based on hierarchy level (Country, State and City). If your data do not have hierarchy, specify the column name in vHierarchyDef variable (For example if you want to reduce data only to Country level, only specify Country
2. For ADMIN, REDUCTION column is empty, means access to all data
3. SALIDIN is able to see only data for ILLINOIS state
4. SK is able to see only data for Chicago city
Another important note, if by any chance your load failed, you can still enter into the script by right clicking the app in work folder (hub) and click open without data and perform changes.
If you face any difficulty, please let us know
Note: Link provided by Carlos is a good starting point to implement security in QS