How to turn off the drop down selection nos??.

Hi, and Welcome to the Apple Community.

Re: How to turn off the drop down selection nos??

Sorry I'm no expert on this, but I don't think there is a way to turn them off.

You might want to check Safari > Preferences > and customise the settings there.

Change Tabs preferences in Safari on Mac – Apple Support

Apple support have tips online for customising a Safari window on MacOS 10.15

but this doesn't customise the History Menu.

Customise the Safari browser window on Mac – Apple Support

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Wondering which model (year) MacBook Pro you are using.

You may want to update your MacOS (latest is Version 12.4) for the latest version of Safari (15.5) to be installed.

(Those drop-down selection nos don't appear on the 15.5 version on my Mac.)

How to Keep your Mac up-to-date – Apple Support

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Re: Also the system became too slow

Wondering if this is just in Safari , or on your Mac generally.

Sometimes third-party (non-Apple) apps (eg: including unnecessary virus checkers) can cause issues. 

Try turning off any such apps., (even "Chrome", etc can cause issues) 

See if there is any change.

if needed: 

uninstall using the uninstaller from the developer.

If your Mac runs slowly – Apple Support

Free up storage space on your Mac - Apple Support

OR

If Safari is slow:

If Safari on Mac doesn't open a webpage or isn’t working as expected - Apple Support

Safari troubleshooting on Mac – Apple Support

If needed:

Safari Support

Safari - Official Apple Support

Mac Support

iMac - Official Apple Support

Hope there's something helpful here.

All the best :-)