convert MOV to mp4

Mov and mp4 are just contains to wrap around the video and audio things inside. If you want to repackage them then for mp4 I usually use the free utility Subler. You open a new file in Subler and drag your .mov to the window. You then save it again and it will automatically do it to .mp4. Note, a .mov could contain video or audio formats that are not supported by .mp4 in which case you will have to recode them using a utility such as Handbrake.

Try to repackage them rather than recode them. Recoding is like making a photocopy of a picture, with inherent loss in quality.

There are many various ways such as online MOV converter tools, VLC Media Player that can convert videos from MOV to MP4. But these methods may not always be successful and do not assure quality of the videos on conversion.

Source: https://www.stellarinfo.com/blog/how-to-convert-mov-to-mp4-video-files-without-losing-quality

Use one of the free methods I outlined, or using VLC or one of the many other free tools. The quality is perfectly fine as long as what you are doing is repackaging and not re-coding. You do not need to buy any product to do this and I would take any advice with a grain of salt that directs you to a commercial software web site and intimating you need to buy something to guarantee results. Some of these sites may have useful instructions such as the one about using VLC (which is free but I find the free Subler a lot easier for doing what you need) but they are posted by companies whose real goal is to get you to buy something so their recommendations are not always without bias.