Can you show a screen shot of what you have set? Are you using IIS?
Could be that the Webserver session needs to be increased.
Are you using IIS or QlikView Webserver?
If you are using QlikView Webserver, you can increase the value in C:\ProgramData\QlikTech\WebServer\config.xml
Regarding not being able to save the file.
If you stop the Webserver service and then try to save it?
Otherwise you have to ask someone that has modification rights on the machine