This Powsershell will set every OneDrive for Business quota to the minimum set below

# This Powsershell will set every OneDrive for Business quota to the minimum set below.
# Quota's that are above the minimum are not changed.
# Richard Artes January 2010
#

# Set the location of the Log file here:
 $LogFile = "c:\temp\quotaSetMinList.txt"

# Set the new minimum GB quota here:
 $minQuota = 100
 $newQuotaMB= $minQuota * 1024

#Your Sharepoint/OneDrive URL goes here:
 Connect-SPOService -Url "https://xxxxxxxxxxxxxxxxxxxxx.sharepoint.com/"

 $oneDriveSites = Get-SPOSite -IncludePersonalSite $true -Limit all -Filter "Url -like '-my.sharepoint.com/personal/'"
 $oneDriveSites | ForEach-Object {
 $site = $_

 $strUserDetails = Get-SPOSite –Identity $site

 # If you want to see what every site's quota is before changes, uncomment this:
 #Out-File -FilePath $LogFile -InputObject $strUserDetails -Encoding UTF8 -append

$QuotaGB = ($strUserDetails.StorageQuota / 1024)

If($QuotaGB -lt $minQuota)
{
Out-File -FilePath $LogFile -InputObject "----User has a quota less than minimum--------" -Encoding UTF8 -append
Out-File -FilePath $LogFile -InputObject $site -Encoding UTF8 -append

$text = "New Quota = " + $newQuotaMB
Out-File -FilePath $LogFile -InputObject $text -Encoding UTF8 -append

Set-SPOSite –Identity $site -StorageQuota $newQuotaMB -Confirm

Out-File -FilePath $LogFile -InputObject "-----         New quota set.          --------" -Encoding UTF8 -append
}
}

 Write-Host "Done! File saved as $($LogFile)."