Revision timing problem

I was out for more than 2 months and when coming back all cards had revision schedules too spaced: either <10m or some months.
I tried to shorten the Maximum Interval, to compress revision times, but it just made things worse: every option Hard, Good, Easy was the same and equal to the maximum interval.
Could not adjust the timing difference for those 3 options.

Set again Maximum interval to 36000 but things are messed. Only the new notes appear normal, most of the older ones never appeared again, and I need to revise them and send them for appropriate revision times.

What can I do now ?

Anki is giving you the chance at a longer next interval based on whether you have already remembered a card during your break – Due times after a break - Frequently Asked Questions . You don’t need to do anything to change it – just grade the card honestly. If you’ve remembered a card this long, you’ve proven you can do that, so there’s no reason to set shorter intervals. If you’ve forgotten a card, click Again, and relearn it.