Recently one of our customers wanted view more than 250 records in CRM Grid records and currently you can only set up maximum up to 250 only.
You can still able to change this in to database directly as mentioned in following steps.
Warning: This change is unsupported
Step 1: Get the user Id and then update Paging Limit as mentioned in following screen print. Change the name of your relevant user to get his user record id and then use then in next query to update relevant record.
Step 2: Restart CRM web site and also clear user’s IE Cache and done!!
Hope this helps!!