Safari Overriding Site Data?

Based on Grant's suggestion, I looked up tabs via Google, and found an excellent article under Safari Help, entitled "Use Tabs for Webpages." It also describes pinning a website. If one keeps the Safari page minimized during the day, instead of shutting it down, the changes that I make to a particular site still remain. This is true if I minimize the site before turning off the computer. But, if I delete the Safari page after using it, I must start from scratch the next time. I open Safari.

Thanks for your response.

This appears to be a possible workaround in that I was able to click-on Back a couple of times to bring up the site with my changes (the system asked if I wanted to re-submit the form again). I was not able to do that subsequently, however, so it looks like I have some experimenting to do.

Sir Grant --

Thanks for the reply. I have been traveling; hence, the tardy reply.

In Google Chrome for Windows, one can edit the Chrome Settings page so that on Startup one can "continue where you left off." The page for tabs is very similar to the page in Safari. The Favorites in Safari are Bookmarks, I believe, and when one selects one of the Bookmarks/Favorites, the URL appears to override the previous selection. In Google Chrome, I am under the impression that all of the tabs are always open, so to speak. When one selects a tab to open, it is not overriding the last tab that had been opened.

Being new to Safari (and to the Mac), I'm not sure that I understood your question with respect to allowing Safari to "save" that info for the web site. How does one go about accomplishing same? (I am using OS X 10.12.6.)

I have Safari version 11.0, (Mac OS X version 10.12.6), but the options under the Privacy tab under System Preferences look nothing like what you posted, and a Flash Player option doesn't even exist. In Googling Safari versions under OS X, I guess one gets the version that is applicable to one's OS X version.

I was looking at Privacy under System Preferences, not Safari Preferences. Mine matches up with yours.

The site that I use is Stockcharts.com. The URL is: http://stockcharts.com/h-sc/ui

This takes you to an initial screen. By scrolling down below the chart of the Dow Jones Industrial Average, there are a host of attributes that one may apply to customize the chart. It is the customized version that I Bookmarked to Favorites in Safari. But, when one returns to this site (fro another site, via the Favorites menu), one is returned to the initial/login screen. And, this is what I am attempting to avoid, since I access this site repeatedly throughout the day. Both Chrome and Internet Explorer handle this procedure slightly differently, but both work.

I would have included a Print Screen version of the web page, but after saving the screen by means of Shift-Command-3, I was unable to insert it into this reply, using Command-V. Still learning!

So, if under Safari/Preferences/Privacy I have checked "Allow from websites I visit" (pertaining to cookies and website data), this would imply that the Bookmarks/Favorites approach used to re-access sites is not the preferred approach in this specialized instance. Which leads us where?