Individual is right in that raw data facts cannot change. However, if there is a fault in the way the original data is collected then the data can be replaced by new correct data. So it seems as though the facts have changed, but in this case the original data weren't valid so technically were never facts. What changes is whether we consider the original data to be true facts or not, but this it doesn't mean that they were ever actually true.*
Another thing that can change about something that we measure is the precision that we measure to and the confidence that we have about the measurement. In science all measured data must be accompanied by a statement about these. Eg., if you see length measurement it will commonly look something like this: 1.230 +- 0.002 m, this tells you that it was measured to four significant digits and the true value of the length is between 1.228 to 1.232 meters.
But, if you correctly measure something once and then measure it again with better equipment and get more precise data then the original data facts are still just as true as they were before because they are true with respect to the precision of the method of measurement.

-- continued below --

-- from above --

However, foxy is sort of right also, because derived "facts" can sort of change. For example, imagine you had a chook that lays eggs. If the true daily egg count was the sequence 1,0,1,0,1,0,1,0,1,0 but you sampled it on the first day and then every second day after then the derived fact of the average number of eggs per day that it lays would by 1 egg a day. However, if you sample it on second day and then every second day after the average egg count would be 0. Here the derived fact of the average is dependent on the sampling regime. Now technically these are two separate and distinct derived facts so there really is no change, but typically when people use words like "average" they would use it in a sense where these two cases are the same thing. The true average of course is 1/2 an egg a day, but to obtain this we needed 100% of the chook's laying data. This happens in real-life, we state derived "facts" on incomplete data, and these facts appear to change when more data becomes available.

A perceived fact can be a complete falsehood, at one time many believed the Earth was flat, but the overwhelming evidence has dispelled that and its no longer a fact in most peoples minds, except of course in the minds of a few old Forumites and Donald Lovers.

Some people like to state a truism as fact, others see their subjective opinion as fact, and finally some through total ignorance see something as fact. AND that's a FACT!

Two people can observe the same data and draw different conclusions, eg The ancient Greeks believed consuming alcohol meant accepting evil spirits into the body. Well we still call it spirits but we know it is not a spirit being influincing our behaviour. The data is the same but the conclusions are different. The facts have not changed but the information to form a conclusion has.

A fact is a verifiable piece of information that
does not alter or waver under any circumstances.
Any piece of information that is verifiable by
any one at any time is a fact. If a piece of information
does not meet this standard it is not a fact.

Facts are not "decided upon." They are discovered.
We did not get together and decide the earth was round.
We proved it. Anyone, anywhere can recreate the
experiment and get the exact same results.

No one performing an experiment accurately will get an
alternative result.

Some people seem to value belief/opinion or feelings over
truth/facts.

A fact can be a fact and then cease to be a fact anymore.
There is always more to learn.

This to-ing & fro-ing re facts reminds of the colours of coral & the subsea environment in general.
We see documentary films that show the colourful underwater world's kaleidoscope. What most people see is the effects of artificial lighting that makes the human eye see the colours which we couldn't see without such lights !
So, which is the real fact here ? Are the colours real or are they not ? ;-)