Whats a good adhesive for gluing back on emblems?

also kinda related topic but my small antenna receiver unit for my keyless entry and security system was attached to the top of the inside of my windshield with the adhesive sticker it came with, its only been a month or so but it keeps falling off now, what should i use to stick it back up there?? also the brain unit of my alarm system which is under the drivers side dash fell down and i just stuck it back up there..............what should i do for that?? dang this what u get for a cheap install job......lol