The maximum file size setting will determine the maximum size of files uploaded to document libraries on the site. You can set the sharepoint 2010 web application max file size limit in many ways, but   I have done this in PowerShell.

I wrote a smart PowerShell script to do this job.

$siteUrl = http://eblogin.com
Write-Host "Connecting to the site"
$SPSite = Get-SPSite | Where-Object {$_.Url -eq $siteUrl}
if($SPSite -ne $null)
{
$SPSite.WebApplication.MaximumFileSize = 200
$SPSite.WebApplication.Update()
}

$SPSite.Dispose()

Hope this will help you.