The large X icon at the upper right of the window closes the entire window and all tabs in it. However, you should find a small x on the tab itself (on the tab bar) to close just the current tab. Other methods include:

• right-click the tab > Close tab
• middle-click the tab
• Ctrl+w to close the current tab

Do any of those suit your needs?

And just in case it's needed, to re-open the last closed tab:

• right-click any other tab > Undo Close Tab
• Ctrl+Shift+t

Yes, thank you very much. After reading your reply, I saw right away what you were talking about and it solved my problem immediately. What a relief. Just goes to show, I haven't learned well enough when my husband says, "Read the screen." Thank you again.