When you open a project created in an earlier version of Logic Pro, audio regions in projects for which the Flex checkbox was selected (turned on) have their Flex & Follow parameter set to On. Audio regions for which the Flex checkbox is unselected (turned off) have their Flex & Follow parameter set to Off.
In Logic Pro, select the audio region.
In the Region inspector, select one of the following from the Flex & Follow pop-up menu:
Off: The region does not follow changes to the project tempo, and is not Flex enabled.
On: The region is Flex enabled, so it follows any manual Flex edits. It also follows any changes to the project tempo.
Bars (On + Align Bars): The region is Flex enabled, and Smart Tempo beat markers are used to conform the region to the project tempo at every downbeat (bar).
Because the region is conformed to each bar, the 1/1 setting is not available in the Quantize menu.
Beats (On + Align Bars and Beats): The region is Flex enabled, and Smart Tempo beat markers are used to conform the region to the project tempo at every beat.
Because the region is conformed to each (1/4-note) beat, the 1/1, 1/2, and 1/4 settings are not available in the Quantize menu.
You can set the default Flex & Follow settings for audio recordings and imported audio files in the Apple Books | PDF