I generated a leger report for one of my clients called "NXT8 Inc" but it contains other client transactions (but all these entries linked to "NXT8". How to correct it?

I'm here to help you correct this, frugalscientific.

That's very strange. Normally, the General Ledger report should show only show the transactions related to NXT8 Inc. To isolate the issue, we can perform some basic troubleshooting steps. It could be that accumulated cache is the culprit behind this unusual behavior.

Start by logging in to your QuickBooks account through a private or incognito window. This mode doesn't save your web searches and site data. Just press the following shortcut keys to launch the window: 

• Ctrl + Shift + N (Google Chrome)
• Ctrl + Shift + P (Firefox)
• Ctrl + Shift + P (Microsoft Edge)
• Command + Shift + N (Safari)

Once done, open the report again. If the transactions from your other clients are now gone, switch back to your normal browser and then clear its cache to enhance your browsing experience and delete the junk files. Utilizing other supported browsers as an alternative can also help resolve the issue. 

Additionally, here's an article that you can read to be guided in managing and personalizing your reports in QuickBooks: Customize reports.

Just tag my name in the comment section if you have any other concerns or questions. I'll get back to you as soon as I can.