Having said that I would like to be able to convert these MOV files so they will play with the present version of quicktime. I do not know how to do that. Can you help me with this.
Without information regarding what codecs were used to generate the files you now wish to transcode, how efficient the codecs are, how compressed the data is, what strategies and settings were used (e.g., anamorphic/non-anamorphic, interlaced/progressive, chroma formats, frame rate, data rates, etc.), as well as, your transcoding goal priorities, it would be difficult to recommend a specific workflow and optimum encoding settings. The only thing I could do at this point is to make some general suggestions.
The first suggestion would be to transcode your older content to an open "standards-based" format like MPEG-4 AVC which is currently being used for everything form cellphone conference calls to internet streaming to Blu-ray videos. That is., to maximize playback across multiple platforms and devices, avoid the use of any proprietary or third-party codecs which might employ hybridization of profile features and target level settings or require use of a specific player or file container.
Another suggestion would be to limit the MPEG-4 AVC encode settings to maximize compatibility for targeted viewers. For instance, limiting use to Main Profile @L3.1 target encode features/settings should provide compatibility with JVT standards in use over the last decade but still easily handle content up to and including high quality 720p30 files requiring video data rates up to 14 Mbps. (I am currently re-encoding my files to 720p24 and 720p30 High Profile @L4.0 but use settings targeted for Main Profile @L3.1 compatibility for older hardware devices running current QT7/QTX/IOS player software.)
The next suggestion would be to use a file container that is compatible with your needs. I normally create 720p24/720p30 H.264/AAC/AC3/Chapter M4V files that are universally compatible will all of my devices (Mac OS X, iPad, iPhone, TV, etc. players), is managed by iTunes, and can be streamed within my home, as well as, over the Internet. The same content could just as easily be handle in an MOV file container but if limited to simple H.264/AAC files, might be more universally playable in MP4 file containers. Therefore, once again, your specific needs and requirements would likely dictate which container is best for you.
The last major consideration would be the transcoding app. If your MOV files contain "legacy" encoded data, I would normally recommend any FFmpeg-based converter software. I normally use the free HandBrake app because it includes both targeted presets for the novice user, as well as, a manual settings GUI for custom encodings by advanced users. In addition, it can be programmed to batch process files—i.e., I typically transcode 12 to 40 TV episodes every night while I am sleeping and currently (as of this writing) have 4,334 episodes that still need to be proofed. If the files are encoded with Apple "Pro" codecs not supported by the QT X player or HandBrake, then I would recommend using MPEG Streamclip or QT 7 Pro for the conversion.
I did see someone say that when you open an older file with new quicktime that it will create a new version of the MOV file that is compatible.
Once again, this depends on the codecs involved. The QT Player uses the AVFoundation structure for playback. If there is a playback problem (i.e., the codecs, file container, or combination of the two is not supported), then the data is analyzed by the Modernizer structure to determine if it can be converted to compression formats natively supported by QT X. (I.e., the Modernizer checks to see if the your system is indeed configured with the required codecs for QT 7 use). If it can be converted (the required codecs are available), then the Converter structure is called to perform the actual conversion. Unfortunately, this doesn't always work correctly. For instance, under Mavericks, QT X with not attempt to convert a file containing DTS audio if Perian is not installed but will attempt the conversion if it is installed. Unhappily, following the conversion, the DTS sourced audio is still not playable. (Have yet to see if this has been corrected under El Capitan.) In most cases, the conversion is successful. However, in some cases the resulting quality may be much lower than expected due to the absence of user control and the quality of the source file.
Here is what I just tried that strikes me as strange. I was able to open and play a MOV file with quicktime. I saved a new version of this, put it up on the website and it still does not play. Then it occurred to me - quicktime played the MOV file from my computer but cannot do so on the website. What is up with that?
Like the evolving QT playback structures now embedded the latest Mac operating systems, the media structures now supporting playback of web content is also evolving. Most browsers are moving away from the use of plug-ins and instead, using the more modern and simpler HTML5 <Video> Element to control browser playback of web content. (See http://www.w3schools.com/html/html5_video.asp) As previously mentioned above, you may need to recode your web pages for better compatibility across the various browsers currently in use. Unfortunately, as you have not provided any URLs for checking, I can only guess that this may be the source of the current problem cited above and may be yet another reason to switch to H.264/AAC content in an MP4 file container as supported by the latest versions of I.E., Chrome, Firefox, Safari, and Opera browsers.