What can i do when im on probation but i cant pay the court and probation fees

A court cannot revoke your probation for an inability to pay your fees, alone, as long as you have put out your best effort to pay those fees.
To show your best effort, keep track of all the times/locations/companies where you apply.  Stay in touch with your probation officer and let them know all of the efforts that you are taking to get employment and remain compliant with your probation conditions.  Communication is really the key here.
Additionally, when you visit with your probation officer, see what help their office may be able to lend you.  Many probation departments have very good working relationships with the Texas Workforce Commission to assist in job placement and retraining (if needed).  Welders, for example, make a very good wage.  You may qualify for a grant to be retained as a welder (or computer operation, nurses aid, etc....).  Also reach out to your local junior college.  Most people think the junior colleges only offer classes for traditional degrees.  However, more and more also offer vocational and job training assistance....and assist with financial aid to pay for the training.  Knowledge is power.  The more you learn, the more you can do.
I have represented several defendants with non-payment issues.  Until they can get on their feet with retraining, I encourage them to look at non-traditional revenue streams.  "Gigs" are not regular work, but they can help pay some of your fees.  Gigs can include donating blood, working clean-up for a concert, or serving on a focus group.  Again, it's not a regular job, but it can provide you the means to get over this hump until you get a regular job.  Plus, if the judge asks you, "what have you done to try to pay your fees," you will then honestly be able to say, "Everything!".
While you are working on these tasks, make sure you comply with all of your other terms.  If you are not working, you should for sure be doing your community service hours.  Even if the state cannot revoke you for non-payment, they can easily revoke you for failure to complete your community service....especially if you don't have a regular job that is tying up your time.
I wish you the best.  Just remember there are resources....it's just takes some persistence to find and tap into all of them.