Ranking position is not a stable thing and what you see is not necessarily what others see. Google specializes in personalized results so they consider your preferences when they show you results. Your results may not be the same as my results for the same search terms. So, no, there is no way to obtain rank stability. It can change hourly.

I will need a little more information.

Is this a situation that has been happening for six months or more on a regular basis?

@martinibuster Its been happening for the past one year(approx.) but during the last one month the ranking has been stable and now it starts changing again.

@not2easy If google is focusing on personalized search results then what's will be the meaning of doing SEO activities in the future. There must be a some factors to rank and obtain a stable traffic flow right. What will be that factor, that we need to focus on?

So this happens to just three pages and all the other pages on the site are stable?

If that is the case then it seems like whenever you update those three pages Google will promote them to the top, which is a normal thing, then figure out where it belongs and re-rank it there. In this case it decides that it belongs at the bottom of page one or on page two.

It sounds like you're working on the pages too often. Just SEO it to the best of your ability then move on, give Google time to figure out where it belongs.

Sometimes it can take months for Google to figure out where a page belongs. Sometimes sooner, depending on how important the site is.

@martinibuster Thanks for sharing your thought but what is the right scale of doing SEO activities, that is on which scale one can determine the SEO activity for a page is enough or not.

@DanielGriffin SEO is regular and ongoing process so not one can say that my SEO activity is enough for my website or any particular page .... If you want to determine ranking for any particular keyword or targeted page just see detail on GSC (google search console) ... You can see there that which pages are ranking for which keywords, so doe your SEO activity accordingly.

What I was saying is that your observations in Google SERPs are not necessarily the same as others who are searching. Like thinkfast said, check the GSC to get their views on your site. Frequent changes that don't improve user experience can confuse your positions and lower your ranking.

One can SEO a page into oblivion by making TOO MANY CHANGES, TOO FREQUENTLY, and TOO OBVIOUSLY chasing serp rank.

Leave it alone for six weeks---at least! All g currently sees is an unstable page(s).

Thanks for all your thoughts and will analyze my works with your ideas.

Oh, one other thing to consider is that the other pages on those SERPs have SEOs that are probably carrying out SEO activity and may be pushing your pages down, or even up.
I wouldn't obsess about it too much, and as others have suggested, leave it and let it settle.

not2easy's comment is especially true for local type results. That's a different algorithm.

• Also, reviews is a different algorithm as well.
  
  
• Medical and financial are different algorithms.

Google is ranking the page where it deserves to rank according to whichever algorithm is in play.

• What that usually means is that something that is present in the top ranked sites is missing in your site.
  
  
• Possibly, there is something present, relative to your site, that shouldn't be there, that is keeping the site from making it to the next level.

Sometimes people say things like,it's not good enough. But it's not always about good or bad. Sometimes it is. Sometimes it isn't about good or bad. There's nuance to this.

Whenever you make changes, apparently what's happening is that Google's system let's you back in to the higher rankings but then (presumably) some other part of the algorithm is pulling it back to where it properly belongs according to whichever algorithm is in play.

These are all general observations, useful hopefully to a lot of people. The nuance is in the specific.

Good luck!

Roger Montti