I am unable to update the bank accounts for some clients.it keeps asking me to try later.

Hello mjinnah2,

It's vital you're able to update your client's bank accounts so you can stay updated with the income and expenses on the account. QuickBooks is designed to help you bring your financials into perspective and it's important you enjoy this benefit. 

First, I'd like to start off by troubleshooting this issue to determine if it's a browser-related issue. Clearing cache and cookies is a great way to clean your browser allowing it to work more efficiently. Here's an article that shows you how to do that: How to clear cache and cookies. If this doesn't work, I suggest using a private/incognito window to see if that works instead. Try this out and let me know what happens.

I'll be one message away in case you need further assistance.