Forced to flex overtime

I, police officer, non-exempt, civil service in Texas, and my co-workers are being forced to flex overtime within the 40 hour workweek, for example: an officer works Monday to Thursday 10 hours a day and works two hours overtime on Monday is being forced to come in two hours later (or to leave two hours earlier) on Tuesday.
Before we have been paid overtime at 1 1/2, but due to budget cuts they try to squeeze it on all corners and ends.
Now since it is within one 40 hour workweek is this illegal ?
Also, since we have been paid at 1 1/2 before, shouldn't time off also be 1 1/2.
And last :o): If any of this is illegal could you provide a source I can show to my co-workers, please.

Thank you for your time :o)

It is not illegal and it is a way of keeping labor costs under control.

However, if you are in a union, you might check to see if this violates the collective bargaining agreement. If you are in a union, but the CBA does not restrict the practice, it could become a topic for discussion during the next contract negotiations.

Texas law does not require daily overtime pay. Comp time may be accrued for overtime (and for police officers, it's not 40 hours a week, but something more-FLSA exception) but it must be at 1.5 time the OT hours (worked 3 hours OT-per the public safety employees exception-accrue 4.5 hours comp).
Again, for anything more than that, you'll have to look to your CBA.

Police officer overtime is measured in 28 day periods. They must have worked in excess of 171 hours in a 28 day period to be eligible for overtime.

It surprised me when I first went to work in a municipality but thats an exception under the FLSA.

Unless specifically barred by contract or CBA, what you are describing as flex overtime is always legal in all 50 states. In those very few states where overtime is calculated on a daily basis (which does not include Texas) it would not eliminate the overtime due, but no law in any state prohibits an employer from controlling the hours worked the way you describe.